air conditioning (ch3)

8/8/2019 air conditioning (Ch3)

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Chapter Three

ImprovedCase


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(3-1) Overall heat transfer coefficient (U) improvement

The first step before any design process for any air conditioning system; engineers must carefully

determine the amount of heat removal needed in summer season and the amount of heat to be produced

in winter season. Before an air conditioning system can be designed, all these loads must be analyzed

and summed up with great care.

There is more than one type of walls and floor sections exist in the structure of the building. So,

overall heat transfer coefficient depends on many different things; greatly it depends on resistivity of

material (R) to the wall components such that:

We try to get a small value of U, so to reduce the value of this factor we made the following:

Increase the insulation thickness in side walls from (2cm to 5 cm ) Adding insulation for roofwith thickness (5cm) Increase the air gap between layer walls .for side walls the air gap has been increased from

(10cm to 30 cm)

Increase the resistivity of the material that constructs the wall by increasing the thickness ofsome materials.

*Those changes are detailed in figures and tables below.


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Side wallheat transmission factor(U)

Figure (3-1a):base case side wall construction Figure (3-1b):improvedside wall construction

Table (3-1):-side wall construction materials& thickness of material and thermal resistance.Material x(m) k(W/m.K) R(m2.K/W)face stone 0.1 1.7 0.06

Concrete 0.15 1.75 0.09

Insulation 0.05 0.045 1.11

air gap 0.3 0.28 1.07

hollow brick 0.1 0.9 0.11

cement plaster 0.025 1.2 0.02

outside air - - 0.029

1nside air - - 0.12

USidewall= 0.383 (W/m2.K)


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Roofheat transmission factor(U)

Figure (3-2a):Base case roof construction Figure (3-2b):Improved roof construction

Table (3-2):-Roof construction materials& thickness of material and thermal resistance.

Material x(m) k(W/m.K) R(m2.K/W)

asphalt water proving 0.02 0.7 0.029

concrete baking 0.05 1.75 0.029

Insulator 0.05 0.045 1.111

Hollow brick 0.14 0.9 0.156

concrete baking 0.06 1.75 0.034

cement plaster 0.02 1.2 0.017

outside air - - 0.029

1nside air - - 0.12

URoof=0.65(W/m2.K)


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(3-1-1)Load saving due to improved U

A) Heating loadfor improved U

*detailed calculation results are in Appendix A

Table (3-3):heating load for base case and improved case due to improving U.

Ground floor First floor Second floor

Load(kW) Ventilation(kW) Load(kW) Ventilation(kW) Load(kW) Ventilation(kW)

Base case 61 26 36 20 65 21

Improved 60 26 33.5 20.4 45.6 22

Load without ventilation( Base case)=162kW

Load without ventilation( improved )=139.1 kW

ventilation Load =67kW

Figure (3-3):Heating load for base and improved case

Percentage saving in heating load

0

25

50

75

100

125

150

175

200

225

250

1 2

Heating load for base and improved case

base improved

%10%100229

1.206229%100

xx

base

improvedbase


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Figure (3-4):Percentage saving in heating load due to improved U.

(B) Cooling Load for improved U

*detailed calculation results are in appendix (A)

Table (3-4):cooling load for base case and improved case due to improving U.

Ground Floor First floor Second floor

Load(kW) Ventilation(kW) Load(kW) Ventilation(W) Load(kW) Ventilation(kW)

Base case 90 19.1 65 15.1 88 16.2

improved 88 19.1 63 15.1 70 16.2

Load without ventilation( Base case)=243kW

Load without ventilation( improved )=221kW

ventilation Load = 50.4kW

saving

10%

90%

Percentage saving in heating load


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Figure (3-5):cooling load for base and improved case

Percentage saving in cooling load

Figure (3-6):Percentage saving in cooling load due to improved U

saving7.5%

92.5%

Percentage saving in total cooling

load

%5.7%1005.293

5.2715.293%100

xx

base

improvedbase


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cost analysis for improved U

Assumptions

n=20years Operating hours = 16hour/day Cooling season=180day/year Heating season=180day/year

Insulation costTable (3-5):prices of unit area of different thickness of insulation.

Roof insulation (5cm) cost = 815(m2) 4($/m2) =3260 $

Side wall insulation (2cm) =1062(m2) (4-2) ($/m2) =2124 $

Total cost of insulation =5384 $

In winter (heating mode)During winter season the HVAC system consists of boiler and air handling units. Heating load

decreases and this will lower the operating cost of fuel new boiler with capacity smaller than that has

been used in base case.

Thickness (cm) Price($/m2)

2 2

5 4

yearliterVyeardayxdayhourxhourtxtxmliterxsmxV

smxm

V

skgkW

VH

Qm

kWQ

fuel

fuel

fuel

fue

fuel

fuel

fuel

heating

/6.6671)/(180)/(16)/(min60)min(sec/60)/(10)/(1043.6

/1043.6827

00053.0

/00053.042032

23

.

23206229

3337

37;


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Where:

H.V: heating value of fuel (diesel) =42032kJ/kg

fuel :diesel density=827kg/m3

Fuel cost (diesel) =1$/liter

Annual saving from fuelyearliter

xyear

liter $6671

$18045

In summer (cooling mode)During summer season the HVAC system will consists of chillers and air handling units. Cooling

load decreases due to the improved U and this will lower the operating cost of electricity but in this casethe same chiller will be used, assuming that the chiller will consume electricity about 22kW

yearkWhQ

yeardayxdayhourkWxQ

kWQ

cooling

cooling

cooling

/63360

)/(180)/(1622

22

Electricity cost =0.15$/kWh

Annual saving from electricity =63360 (kWh/year) x0.15 ($/kWh)

Annual saving from cooling =9500$/year

Payback period monthsaving

t)4

80459500

5343cos


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(3-2) shading coefficient improvement

Shading coefficient is the measure of solar energy transmittance through glass. it is divided into

two parts primary and secondary solar transmittance ;primary solar transmittance is defined as the

fraction of solar radiation that enters directly through windows compared to the total solar insolation,

and secondary solar transmittance defined as the fraction of solar radiation that absorbed in window or

shading device compared to the total solar insolation.[4]

In passive solar building design the aim of the designer is normally to maximize solar gain

within the building in the winter (to reduce space heating demand), and to control it in summer (to

minimize cooling requirements) [4]

The effect of solar radiation on load is satisfied by equation

Where:-

SHGF:-solar heat gain factor

SC:-shading coefficient

A:-area of glass

CLF:-cooling load factor

Shading coefficient factor in base case was equal to 0.95(no indoor shading)and it has been improved

to be equal to 0.55 by using a Venetian blinds light type.

Table (3-6):shading coefficient factor for different types of materials. [2]

venetian blindsroller

shades

type of glassThickness

(mm)

no

indoor

shading

medium light dark light

single glass

Table(3-6),continued

)()()()( CLFxAxSCxSHGFq
http://en.wikipedia.org/wiki/Passive_solar_building_designhttp://en.wikipedia.org/wiki/Space_heatinghttp://en.wikipedia.org/wiki/Space_heatinghttp://en.wikipedia.org/wiki/Passive_solar_building_design


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regular sheet 3 1 0.64 0.55 0.59 0.25

Plate 6--12 0.95 0.64 0.55 0.59 0.25

heat

absorbing6 0.7 0.57 0.53 0.4 0.3

10 0.5 0.54 0.52 0.4 0.28

double glass

regular sheet 3 0.9 0.57 0.51 0.6 0.25

plate 6 0.83 0.57 0.51 0.6 0.25

reflective 6 0.2-0.4 0.2-0.33

Load saving due to improved SC

Reducing the shading coefficient will reduce the cooling load and this is obvious from the following

tables and detailed calculations.

Cooling load for improved SC

Table (3-7):solar load for base case and improved case due to shading factor improvement.

Case

Ground floor

Load (kW)

First floor

Load (kW)

Second floor

Load (kW)

Total

(kW)

Base case 16.6 16.3 10 42.9

Improved case 9.6 9.4 6.4 25.4

saving 7 6.9 3.6 17.5

*detailed cooling calculation results are in appendix (A)

Percentage saving in solar load

Percentage saving in total cooling load

%40%1009.42

4.259.42%100

xx

base

improvedbase

%9.5%1005.293

276293%100

xx

base

improvedbase


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Figure (3-7):cooling load for base case and improved case due to shading coefficientimprovement.

Figure (3-8):Percentage saving in total cooling load due to shading coefficient improvement

Cost analysis for improved SC

Venetian blind cost (unit) =25 $/unit

Number of windows in hospital =146

Total cost of Venetian blind=146x25=$3650

A new chiller will be selected for the two improvements (shading factor coefficient SC and overall

transfer coefficient U)

saving

6%

94%

Percentage saving in total cooling load


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Total cooling load after improving U and SC is changed from 293.5kWto 254kW.then chillerwill be

changed from 305kW with input power=108kW (electrical) to 282kW (30GX082) from Carrier

company with98kW(electrical), so it saves about 10kW electrical

Summer season =180 day/year

yearkWhxyearkWhngannualsavi

yearkWhQ

yeardayxdayhourkWxQ

cooling

cooling

/$4320/$15.0)/(28800

/28800

)/(180)/(1610

And annual saving by fuel=8045 $/year

Total cost of shading (venetian blind) =7560 $

And total cost of insulation =5384 $

Payback period (insulation and shading) yearyryrsaving

t1

/$8045/$4320

$5384$7560cos


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(3-3) Lighting improvement:

Lighting can make a big difference to the energy bill. Low energy bulbs will save money, last longer

and are more economical long-term. If we use a particular light for an average of four hours or more a

day, then we replace it with an energy-saving equivalent, using around a quarter of the electricity and

lasting up to 12 times longer. So we think about this kind of lamps which saving energy and we decided

to change the Conventional Incandescent Lamp (CIL) with Compact Fluorescent Lamp (CFL) to

make an efficient improvement for our case study (Al-Kuwaiti Hospital).

Compact Fluorescent Lights:

Fluorescent lights and especially the compact fluorescent lights, also called CFLs, are a more eco-friendly lighting solution than incandescent lights. Fluorescent light bulbs have had a bad first

impression to brighten. The long-term economical savings and reduced maintenance for changing longer

lasting florescent light bulbs were first taken advantage of in commercial and institutional properties.

Fluorescent light bulbs also debuted with an annoying lighting lag time.

The real advantage is in CFLs, which use 75% less electricity and last ten times longer. One

incandescent bulb replaced can reduce CO2 emissions by 67 pounds over the lifetime of the bulb.

The drawback of course is that CFLs are often at least 4 times the price of our old familiar

incandescent light bulbs. Of course over time the savings of incandescent light bulbs is lost in electricity

and replacement cost. Another drawback of CFL bulbs is that they contain a small amount of mercury

and therefore must be recycled properly in a city or county collection center for CFLs. [5]

What should we take into Account When Buying Lamps?

Color renderingThe color rendering of a lamp describes how natural surroundings appear in its light.

EfficiencyEfficiency is the amount of light emitted by a lamp for each Watt of power consumed. Different lighting

technologies are available with different levels of efficiency.


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LifetimeThe lifetime of the lamp influences both the relative purchase price and replacement costs. Different

factors influence the lifetime, such as switching cycles, ignition, run-up and starters. [6]

Advantages of Compact Fluorescent Bulbs:

Compact fluorescent light bulbs last up to ten times longer than incandescent bulbs. Generally, anincandescent bulb lasts less than 1,000 hours while a compact fluorescent bulb lasts about 10,000 hours.

Compact fluorescent light bulbs save money. Although they initially cost more than incandescent bulbs. Compact fluorescent light bulbs use 75 to 80 percent less electricity than incandescent light bulbs and

thus are more energy efficient.

Compact fluorescent light bulbs emit less heat than incandescent light bulbs. About 90 percent of theenergy emitted by incandescent bulbs is heat, compared with around 30 percent released by compact

fluorescent bulbs.[7]

Comparison between CFL & CIL:

To make a comparison for wherever you live, just substitute your own local currency and costs

for the particular lamps you want to use (lamp purchase prices, cost of labor for lamp replacement and

unit costs for electrical energy) and then you just have to do all the calculations.

Table (3-8):Comparison between CFL and CIL types

Type

Cost

($/unit)

Life Span

(hr)

Power Rating

(Watt)

CIL 0.5 1000 60 watts

CFL 3.5 6000 15 watts

Any total money savings will depend on several things:

How much a lamp is used over a particular period of time.


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The purchase price of the lamp. The cost of installing/replacing the lamp.

Figure (3-9a)Compact Fluorescentlamp [8] Figure (3-9b): Conventional Incandescent lamp[8]

The following table and figure define us how we can compare between the normal lamps and the energy

saving one.

Table (3-9): luminous of the CIL and CFL lamps

Luminous flux

(light output)

Conventional Incandescent

Lamps

Compact

Fluorescent Lamps

200 lm 25 W 5-6 W

450 lm 40 W 7-10 W

600-700 lm 60 W 11-15 W

950 lm 75 W 16-20 W

1200 lm 100 W 21-25 W

1600 lm 125 W 26-30 W

1900 lm 150 W 31-42 W


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Figure (3-10): Electricity usage of different types of light bulbs at different light outputs. [9]

The chart shows the energy usage for different types of light bulbs operating at different light outputs.

Points lower on the graph correspond to lower energy use.

Calculation of Load Lighting using CFL:

For lamps using the following equation:

CLFffgLampsRatinq bu # of lamps (3-1)

Where:

Lamps rating = 60 Watt.

Fu = utilization factor (use factor defined as the ratio of wattage in use possibly at design condition to

the installation condition) =0.9 [in Hospitals].

Fb =ballast factor: measurement that compares the ratio of light output of a lamp to the light output of

the same lamp or lamps operated by a standard reference ballast) = 1.2 [for CFL]

CLF = Cooling Load Factor = 0.9 [in Hospitals]. [2]

Wattage = Area U (3-2)
http://upload.wikimedia.org/wikipedia/commons/e/e7/Electricity_use_by_lightbulb_type.svg


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Where:

Area: area of the space in (m)

U: factor equal in hospitals = 21.52 (Watt/m)

[but it different in ICU rooms to be equal to 30 (Watt/m)]

Figure (3-11): samples of CFL lights. [6]

Table (3-10):lighting load for base case and improved case due to improving type of lights.

FloorNo of

lamps

Base case

Light load

(kW)

Improve

d light

load

(kW)

Load saving

(kW)

Ground

floor

304 14.8 4.4 10.3

1st

Floor 280 13.6 4.0 9.5

2nd

Floor 259 12.6 3.8 8.8

Total 843 41 12.2 28.6

Base case total cooling load =293.5 kW

Improved case total cooling load =268.4kW


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Figure (3-12):Comparisonbetween base case and improved case due to lighting improvement.

Percentage saving in cooling load

Figure (3-13):Percentage saving in cooling load due to lighting improvement.

0

50

100

150

200

250

300

350

1 2

(kW)

base improved

(cooling load for base case and improved case due to lighting improvement )

%7.9%100297

5.267297

x

base

improvedbase

9.7%

saved

90.3%

(Percentage saving in cooling load due to lighting improvement)


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Cost analysis for improved lighting case

CFL Saving in Chiller Load

For this improvement the chiller load is changes from 297kW to 268kW then a new chiller is tobe selected.

The new chiller is 30GX082 from Carrier Company with net nominal cooling capacity =282kW

and nominal input power =98kW (electrical)

Energy saving due to lighting improvement is divided to:

a) Electricity consumption by chiller is reduced due to reduce input power.

Chiller input power saving =108-98=10kW (electrical)

yearkWhxyearkWhngannualsavi

yearkWhE

yeardayxdayhourkWxE

chiller

chiller

/$4320/$15.0)/(28800

/28800

)/(180)/(1610

b) Electricity consumption for lighting is reduced due to using new type of lights

CFL saving in lighting Electricity consumption

Table (3-11):comparison between CIL and CFL lights

According to CIL CFL

Life Span (hr) 1,000 6,000

Price per unit ($) 0.5 3.5

Power Rating (W) 60 15

Energy Consumption (kWh) 295,387 73,847

Energy Cost ($) 44,308 11,077

Total price (for 843 units) $ 421.5 2,951


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Rating power for base case lights =0.06kW/unit Rating power for improved case lights=0.015kW/unit Number of units in whole hospital =843 units Number of burning hours =16365=5840 hr/year Price of kWh electricity=$0.15Energy consumption saving =

[ # of units (Power rating of base type-power rating of improved type) Number of burning hours

per year]

= 843 (unit) (0.06-0.015) (kW/unit) (5840) hr/year

Energy saving = 221540.4kWh/year (electrical)

Annual saving = 221540.4(kWh/year) (0.15$/kWh)=33231$/year

Annual saving = Energy consumption (kWh) Electricity price ($/kWh)

= 295,387 kWh 0.15 $

So the value of saving per year = 33,231 $/yearPurchasing Cost:-

Purchase cost=Purchase cost of base case lightspurchase cost of improved case lights

Purchase cost (difference) = 421.5-2951= $2529.5

Payback period of new lights = ($) ( $ )=2529.533231 = 0.07


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(3-4)Medical waste incinerationMedical Waste in Palestine:

Medical Waste is defined according to the executive lists of the administration of medicalwastes for the year 2008 as the liquid or gaseous amount produced form any medical association due tothe equipment use for analysis and medical care inside or outside the association, these include non

dangerous, dangerous and pathology wastes.

Production of medical wastes in Palestine:

Nowadays estimations shows that the amount produced of medical wastes is 1,29 Kg/bed/day

in the west bank, and 1,3 Kg/bed/day in Gaza; with a whole of about 472,9 tons / month in both Gaza

and west bank from all associations, 374,9 tons in west bank and 98,0 tons in Gaza[15] .

Medical wastes effect on health and environment:

Medical wastes contains big amounts of dangerous transferable elements of microbes and quick

spread dangerous viruses on humans, this may cause mutations and up normalitys forhuman beings in

surrounding areas. Hence being effected by viruses e.g. aids virus or liver cirrhosis

are the most dangerous and counted viruses and these may transfer either by not meant traffic accidents

which are caused by direct contacts itch or injury with defected medical wastes.

Also liquid medical wastes include dangerous chemical mixtures and heavy elements e.g. mercury; this

will affect the various environmental elements such as soil and water. [15]

Figure (3-14) samples of medical wastes [10]


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Hospital Waste

Hospital waste is generated during the diagnosis, treatment, or immunization of human beings or

animals or in research activities in these fields or in the production or testing of biological. It may

include wastes like sharps, soiled waste, disposables, anatomical waste, cultures, discarded medicines,

chemical wastes, etc. These are in the form of disposable syringes, swabs, bandages, body fluids, human

excreta, etc. [11]

This waste is highly infectious and can be a serious threat to human health if not managed in a

scientific and discriminate manner. It has been roughly estimated that of the 4 kg of waste generated in a

hospital at least 1 kg would be infected.[11]

Surveys carried out by various agencies show that the health care establishments are dont care

to their waste management. After the notification of the medical Waste (Handling and Management)

Rules, 1998, these establishments are slowly streamlining the process of waste segregation, collection,

treatment, and disposal. Many of the larger hospitals have either installed the treatment facilities or are

in the process of doing so. [12]

In this project we will use the solid waste from the neighboring hospitals (Al-Sheikh Zayed

Hospital, Ramallah Hospital, Al-Bahraini Hospital and Al Kuwaiti specialized Hospital).

Figure (3-15) percentage of medical waste in hospitals[13]

paper

30%

plastic

30%

hazardious

waste

10%

food10%

metal

10%

glass

10%

Percentage of Hospital Waste


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Classification of hospital waste

(1) General waste: Largely composed of domestic or house hold type waste. It is non-hazardous to

human beings, e.g. kitchen waste, packaging material, paper, and plastics.

(2)Pathological waste: Consists of tissue, organ, body part, human foetuses, blood and body fluid. It is

hazardous waste.

(3)Infectious waste: The wastes which contain pathogens in sufficient concentration or quantity that

could cause diseases. It is hazardous e.g. culture and stocks of infectious agents from

laboratories, waste from surgery, waste originating from infectious patients.

(4) Sharps: Waste materials which could cause the person handling it, a cut or puncture of skin e.g.

needles, broken glass, saws, nail, blades, and scalpels.

(5)Pharmaceutical waste:This includes pharmaceutical products, drugs, and chemicals that have been

returned from wards, have been spilled, are outdated, or contaminated.

(6) Chemical waste: This comprises discarded solid, liquid and gaseous chemicals e.g. cleaning,

housekeeping, and disinfecting product.

(7) Radioactive waste: It includes solid, liquid, and gaseous waste that is contaminated with

radionuclides generated from in-vitro analysis of body tissues and fluid, in-vivo body

organ imaging and tumour localization and therapeutic procedures.

Basic steps to manage the Medical Waste:

The steps of manage the medical Waste are:

1. Segregation of waste

The waste was segregated separately, according to its characteristics, at the point of generation,

mainly from the patient care areas. The hospital used color bags and sharp boxes for easy identification

and segregation of medical solid waste. Non-infectious and domestic type of waste was collected in

black bags, placed in bins while the highly infectious and hazardous wastes was collected in red, yellow


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color-coded bags placed within bags labeled with an infectious waste that can be treated with

incinerator, the sharp wastes collected in the sharp boxes.

Both types of waste were collected twice a day, once in the morning before 8 am and once in

the evening before 6 pm. However, the waste from the Intensive Care Units (ICU) was collected more

often, depending on the number of operations and cases attended in any particular day.

Figure (3-16) segregation of medical wastes into bags[14]

2.Packaging:

Infectious waste was packaged to: (i) protect waste handlers and the public from possibleinjury and disease that could result from exposure to the waste and (ii) avoid attraction to rodents and

vermin. The integrity of packaging was preserved during handling, storage, transportation and treatment.

Objects that are capable of puncturing or cutting including syringes with needles, scalpels, blades,

pipettes and broken glass, were put in puncture-proof containers. The needle tips were first destroyed by

shredding. Later, these materials were disinfected prior to incineration by soaking them for a period of at

least 30 min in a freshly prepared 1% hypochlorite solution before discarding them in the bins.[15]


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3. Collection and Transportation

The collection of infectious and non-infectious wastes was undertaken by two teams of two

members each, one for pulling the cart and distributing empty bags and the other member for sealing the

bags, putting the bags into the cart and replacing the bins with bags. The staff was aware of the potential

hazards of the material they were handling and were found to take requisite protective measures. They

wore impervious gloves and masks during collection of infectious waste, segregation of various color-

coded containers and transporting waste in the designated cart, taking adequate precaution to prevent

any spillage from the plastic bags. [15]

4.Final disposal

Non-infectious waste need not be treated. Medical solid waste comprising: (i) human

anatomical waste, (ii) microbial and biotechnology waste, (iii) sharps, (iv) soiled waste, (v) discarded

medicines and cytotoxic drugs were collected in red and yellow color- coded bags and disposed of in an

incinerator. The local municipal authorities transported the segregated non-hazardous general waste

collected in black bags every other day for suitable disposal. [15]

5.Non incinerating waste

You have to get rid of these wastes in far places without missing their hazardous effect on

the environment.

Air Pollution Control:

Emissions from hospital waste incinerators are of a major concern. The rates of the emissions

depend on the waste feed where the pollutant generating material is removed. The emission rates can

also be reduced by properly operating the incinerator and also by implementing the appropriate APCD.

The common types of emission include particulate matter, toxic metals, toxic organics, carbon

monoxide (CO), hydrogen chloride (HCl), sulfur dioxide (SO2), and nitrous oxides (NOx).


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The following flow chart shows the steps of managing the medical waste in general

Figure (3-17)steps of managing the medical waste

Medical Waste

Non Hazardous

Waste

Hazardous

Waste

Black & Yellow

Bags

Red Bags

Packaging Packaging

Collection &

Transportation

Collection &

Transportation

To the

Incinerator

To far places

to get rid


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(3-4-1)Incineration of hospital wastes

Particularly in underdeveloped countries, there is a huge concern about the disposal of infectious

waste generates by hospitals due to the fear of the spread of viruses and exposure to the toxic metals and

organics. Incineration is still the best way to dispose of medical wastes in many countries around theworld. Some of the benefits provided by incinerating medical wastes are the sterilization of pathogenic

wastes and the reduction of volume by 90 percent to reduce handling and transportation of the wastes,

onsite treatment plants are a viable option.

Incineration may sound as a viable option for many of the waste problems, but it isnt without

some cost. An incinerator has to remain above 800C for a complete combustion of medical waste and to

reducing the risk of exposure of infectious wastes. Hospital incinerators emit various numbers of

pollutants and viruses. So it is not only important but also necessary to include an air pollution control

device for the incinerators.

As a rule, the waste incinerators at hospitals

consist of a furnace with an incineration chamber. In

the furnace, the waste is degassed and the remaining is

incinerated. Burn-out of the generated gases occurs in

the after-burning chamber. In both parts of the process,

the temperature is regulated by way of burners.

The installations at the hospitals are operated

only during the day. At start-up, the furnace is heated

using the available support burners and, if required, the

burning of domestic hospital waste. Every day, after the

last charge of waste has been dosed, the furnaces are

kept at temperature for another 1-2.5 hours using the

burners. Subsequently, the furnace is cooled by leading

ambient air through it for a number of hours. Figure (3-18)incinerator[10]


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Incinerator Equipment and Operation:

To illustrate the operation of an incinerator we will make a selection for one to put it in the

hospital. It is important to note that whilst every medical waste incinerator differs, the basic components

of each incinerator are similar in concept and operation.

The air incinerator consists of four basic sections, as follows:

Loader and bin tippler.

Primary combustion chamber.

Ash discharge conveyor. Secondary combustion chamber.

Loader and Bin Tippler

The function of the incinerator loader is to permit the introduction of waste materials directly

into the incinerator primary chamber.

Primary Chamber

The stepped hearth primary chamber consists of 3 stationary hearths on which the waste burns.

Each hearth is equipped with an ash pusher for the purposes of pushing the burning materials

and ash from the hearth; as this waste is pushed through the incinerator it progressively burns to produce

a mixture of volatiles and ash. Each zone of the hearth is equipped with a combustion air supply.

The final stage of the stepped hearth incinerator is the burnout hearth. It is on this hearth, that the

carbonaceous matter generated in the controlled air environment is contacted with excess air to burnout

the carbon to an acceptable level.

Controlled air biomedical waste incinerators are designed to operate under reducing conditions,

conditions that are well suited for combustion of clinical waste due to its volatility and high energy

content. Reducing conditions involve using less than the stoichiometric quantity of combustion air

necessary for complete combustion in the primary chamber. By starving the process of air the volatile

components of the waste are gasified.


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The combustible gases produced can be considered to be a fuel and are mixed with air to be

completely combusted in the secondary chamber after ignition by a gas burner in the ignition zone. This

process reduces the need for high quantities of auxiliary fuel and minimizes the incombustible

particulate carryover from the primary chamber to the secondary chamber and subsequently to

atmosphere or the air pollution control plant.

Ash Pushers

The primary combustion chamber is equipped with three hydraulically operated ash pushers,

designated 1, 2 and 3, which are used to transfer burning waste through the incinerator. The ash pushers

are operated in sequence at the start of every load cycle. The pushers are of a refractory lined steel

construction, with de-mountable cast alloy steel nose support plates, and are normally retracted but

operate by sliding directly on a cast abrasion resistant section of the hearth.

Figure (3-19) medical waste incinerator Combustion zones-Primary and secondary stages[16]

Ash Discharge Conveyor

This unit is a heavy-duty mild steel construction and is equipped with a heavy loose-link drag

conveyor chain, to which a series of mild steel flights are attached at regular intervals. The chain is

supported on sprockets and a series of troughs attached to the main incinerator casing.

These troughs are fitted with bottom wear plates and drain back to a water bath. The chain runs

through a water bath, which is used to cool the hot ash, prior to it being discharged into an ashbin.


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Secondary Chamber

The function of the secondary chamber is to ensure virtually complete breakdown of all

combustible gases generated in the incinerator primary chamber. This is achieved by maintaining the

secondary chamber at a temperature of over 1000C whilst ensuring an adequate supply of combustion

air. An efficient secondary chamber is essential to minimize emissions of dioxins and other products of

incomplete combustion.

Figure (3-20) Basic Design of Major Biomedical Waste Incinerators [16]


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89

Hazardous Waste

Different types of hazardous wastes are generated at health care facilities. Xylene, methanol, and

acetone are frequently used solvents. Other chemicals include toluene, chloroform, methylene chloride,

trichloroethylene, ethanol, isopropanol, ethylene acetate, and acetonitrile.

Formaldehyde wastes (Formalin solutions) are found in pathology, autopsy, dialysis, nursing

units, emergency room, and surgery, among others. Chemotherapy wastes (e.g., Chlorambucil, Cytoxin,

Daunomycin, etc.) account for a large volume of hazardous waste in some hospitals.

Note that a few states specifically require incineration for chemotherapy waste. Other hazardouswastes include photographic chemicals used in radiology, disinfecting solutions (e.g., glutaraldehyde),

and maintenance and utility wastes in facility engineering. Mercury is a problem found in many

facilities.

Table (3-13) Categories of infectious waste [13]


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90

(3-4-2) Non-incinerating hospital wastes:

Figure (3-21): percentage of non-incinerating hospital waste. [15]

Health care workers should be aware of how regulated medical waste is defined in their state and

institution and any specific requirements pertaining to their disposal.

Some countries explicitly include cultures and stocks from research and industrial laboratories or

from the production of biological. Several states may regulate only contaminated sharps, while others

include unused sharps. Others include chemical waste, such as chemotherapy waste or waste

contaminated with pharmaceutical compounds, as part of regulated medical waste. Some regulations

include a provision allowing a state authority to designate additional categories not previously

considered.

10%

metal

10%

glass10%

hazardious waste

70%

incenerating

waste

Incinerating and non incinerating waste


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91

(3-4-3)Heating value measurements and economical analysis for incineration

"The heating value or calorific value of a substance, usually a fuel or food, is the amount of

heat released during the combustion of a specified amount of it. The calorific value is a characteristic for

each substance. It is measured in units of energy per unit of the substance, usually mass, such as:

kcal/kg, kJ/kg, J/mol, Btu/m." [4]

Heating value of substances can be measured by calorimeter; the figure below shows the

structure of a typical calorimeter.

Figure (3-22):-Cross section for a typical calorimeter[19]

After preparing the sample to be tested in the calorimeter, the sample is fixed in the cup inside

the bomb which is merged inside the water, the fire wire will burn because of electrical source, all the

sample inside the cup will fully burned ,the heating value will appear on digital screen .the principal of

the calorimeter depends on the temperature difference between the initial and final states (before and

after the combustion)according the equation below

= ( ) ( 3-4)

Where
http://en.wikipedia.org/wiki/Substancehttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Foodhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Caloriehttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/Mole_%28unit%29http://en.wikipedia.org/wiki/British_thermal_unithttp://en.wikipedia.org/wiki/British_thermal_unithttp://en.wikipedia.org/wiki/Mole_%28unit%29http://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/Caloriehttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Foodhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Substance


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92

E: process heating power (kJ)

=mass flow rate of heat transfer fluid (kg/s)

Cp: specific heat transfer fluid (J/kg.K)

Ti: inlet temperature of heat transfer fluid (K)

To: outlet temperature of heat transfer fluid (K)

As has been discussed before, the incinerated materials of hospital wastes are about 70% of total

hospital waste includes food (10%), paper (30%) and plastic (30%).heating values of these materials are

detailed in the following table

Table (3-13):-Percentage of incinerated materials of hospital waste and their heating values

Material %from hospital waste Heating value(kJ/kg)

Food 10 20430

Paper 30 15000

Plastic 30 44194

Food heating value of food has been prepared in Healthy and environmental Center of Birzeit

University

Total heating value of incinerated hospital waste

H.V=[%. +%. +%.]

H.V=0.315000+ 0.120430+ 0.344194 = /

According to the draft master plan for health care waste management the average quantity of

solid waste generated per bed per day equals 1.26kg/bed/day. Number of beds in AlKuwaiti hospital

=100 bed

Total heat that can be generated by Al-Kuwaiti hospital

Q=19801 1.26

.

100 24 60 .60 . = 28.87

Which means that heat from hospital waste =288.76W/bed

This heat will be used for the purpose of steam generating for sterilization


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93

Such hospital needs a steam boiler of 65 kW this will cause us to use the apparent hospitals wastes to be

incinerated to compensate for our base case hospital where Al-Bahraini hospital consists of 100 bed and

Al-Sheikh Zayed about 50 beds. Then the total power that can be generated is equal to

Q medical waste=. = 72.19

Economical analysis

Steam boiler fuel consumption

=

. =65

45900 (0.870 )

8.60.60 = 46.8/

Steam boiler annual fuel cost =16848 $ /year

Incinerator annual fuel consumption =7l/day

Annual fuel cost of incinerator =7 x 360=2520 $/year

Difference in prices = incinerator pricesteam boiler price

100,000 -5,600=94400$

Annual saving =annual fuel cost of steam boilerannual fuel cost of incinerator

Annual saving =14328 $

Payback period =

=6 .5 years


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94

(3-5)Improved Case Equipment Selection

(3-5-1)Chiller Selection:

We have a 68 kW saving energy in cooling case so we want to select a new chiller consistent

with the new load to achieve the goals of saving, so the new chiller is: AIR-COOLED LIQUID

CHILLER Module and the selection was based on the Carrier Products Catalogue, the following data

was obtained.

1. The chiller used was selected to be an Air-Cooled because it can handle the large load we had.2. 30 GK series3. The load required for the cooling coil was found to be 229kW4. This series can cover 238-725 kW (Model 30GK 085) has the following properties: Net nominal capacity =238kW = 68 TR Operating weight of 2730 kg Semi hermetic compressors, 4 or 6 cylinders , 24.2 r/s R-407C used as refrigerant Copper tubes and aluminum fins condensers Number of control steps =8 Nominal Unit Power input of 97 kW

Note: More details in Appendix(C)


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(3-5-2)Air Handling Unit selection (AHU):

Because of the reducing of the load due to the improvements that we did, which results in saving

by 68 kW in cooling and 33 kW in heating the capacities of the AHUs differs, so we should make a

new selection for a new load, so the new AHUs are :

1. (Model 39CD-350) for load of (107kW).2. (Model 39CD-340) for load of (83kW).3. (Model 39CD-230) for load of (38 kW).

We selected a 39CD/CX/CH Central Station Air Handling Units Module and the selection

was based on the Carrier Products Catalogue, the following data was obtained.

(Model 39CD) has the following properties: 23 different basic sizes with an air flow range 280 to 26400l/s. Static pressure up to 3000 pa. Complete range of matching equipment modules and accessories. Customized and site assembly versions available. Heating and cooling coils mounted on slide tracks for easy removal.

Note: More details in Appendix(C)


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(3-5-3)Boiler selection:

We have a 33 kW saving energy in heating case, so we want to select a new boiler consistent with

the new load to achieve the goals of saving, so the new boiler is:

MODEL,NXR 3-38

With a range capacity (210-250) kW, so it covered our load which are 250 kW.

1. Technical data : Net output= 250 kW = 853795Btu/hr = 215157 kcal/hr Number of sections = 8 Water content = 1,664 L The boiler contains a burner already. Weight = 920 Kg Max operating pressure (primary) = 6 bar Efficiency = 93 %

The boiler required to cover the load is selected from the CHAPPEE NXR 3, this type belong to the

new range of cast iron sectional boilers. It has been designed to operate on oil or gas fuel.

Note: More details in Appendix C


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(3-5-4) Pumps Selection

In order to select any pump, two main properties should be taken into consideration:

1.Total Head loss which is the sum of all pressure drops across equipments and the head loss due tofriction, which differs from base case because of reducing the load, so we want to calculate a new

head for the pumps.

2.The flow rate, which also differs because of the same reason above.Chilled Water pump

Here we assume that: V =2 m/s, for steel pipe = 0.000046, water = 1000 kg/ m3

Table (3-14): Chilled Water Pump hfCalculations

Name of

Dia.

Pipe

Dia (in)/D

Total

length

[m]

Reynolds

no. hf(m)

Main 1 3 0.0006 36 127140 0.02 1.76

AHU 1 2 0.0008 10 87097 0.0218 0.78

AHU 22 0.0009 10 76710 0.0227 0.92

AHU 3 1 0.0014 10 51905 0.0257 1.54

hf= 1.76+ 0.78+ 0. 92+ 1.54= 5m

Table (3-15): Chilled Water Pump hmCalculations

Name of

Dia.

Pipe

Dia

(in)

Check

Valves

no.

K

Gate

Valves

no.

KElbow

no.K Tees K hm(m)

Main 1 3 4 2.1 4 0.16 5 0.95 4 0.9 3.46

AHU 1 2 1 2.1 2 0.16 0 0.95 1 0.9 0.66

AHU 2 2 1 2.1 2 0.16 0 0.95 1 0.9 0.66

AHU 3 1 1 2.1 2 0.16 0 0.95 1 0.9 0.66


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hm = 3.46+ 0.66+ 0.66+ 0.66 = 5.43m hp = 0+ 5.43 + 5 = 11m + 3 = 14m We added 3m to the head of the pump to compensate any losses in the AHU or any other

losses.

To evaluate chilled water flow rate, we need to do the following.

From chiller data sheet

Tsupply = 7oC

Treturn = 12oC

Where:

Tsupply = supply chilled water temperature.

Treturn = return water temperature.

wm

= chilled water flow rate.

= (chiller capacity/ hw)

= 228 / (50.83-29.4) = 10.64 kg/sec= 0.01064 m3/s

wm = 38.3 m3 / hr From Salmons general catalogue, required pump is, Model , 40-125-H1 (2poles - 50Hz, DN 65-40 )


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Hot Water Pump:

The same procedure followed in chilled water pump we found the following:

Table (3-16): Hot Water Pump hfCalculations

Name of

Dia.

Pipe

Diameter

(in)

/D

Total

length

[m]

Reynolds

no. hf(m)

Main 1 2 0.0011 16 66566 0.024 1.80

AHU 1 1 0.0016 24 44355 0.0262 4.41

AHU 2 1 0.0021 18 33680 0.0289 4.81

AHU 3 1 0.0029 12 23815 0.0295 4.63

DHW

1 0.0023 40 30937 0.0293 11.79

hf= 1.8+ 4.41+ 4.81+ 4.63= 15.65 m For Domestic Hot Water hf = 11.79 m

Table (3-17): Hot Water Pump hmCalculations

Name of

Dia.

Pipe

Dia

(in)

Check

Valves

no.

K

Gate

Valves

no.

KElbow

no.K Tees K hm(m)

Main 1 2 2 2.1 2 0.16 3 0.95 2 0.9 1.83

AHU 1 1 1 2.1 2 0.16 0 0.95 1 0.9 0.66

AHU 2 1 1 2.1 2 0.16 0 0.95 1 0.9 0.66

AHU 3 1 2.1 2 0.16 0 0.95 1 0.9 0.66

DHW 1 2 2.1 5 0.16 5 0.95 4 0.9 3.50


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hm = 1.83+ 0.66+ 0.66+ 0.66= 3.81m For Domestic Hot Water hm = 3.5 m hp= 0 + 3.81 + 15.65= 20 m + 3 = 23 m For Domestic Hot Water hp= 12 + 3.5 + 11.79 = 28 m For Domestic hot water [ Z =12 m ]

To evaluate hot water flow rate, we need to do the following.

From boiler data sheet

Tsupply = 80oC

Treturn = 60oC

Where:

Tw1 = supply hot water temperature.

Tw2 = return water temperature.

mw = hot water flow rate.

mw= (boiler capacity/ hw) mw = 250 / (334.92-251.09) = 3Kg/sec Vw = 0.003 m3 /s = 10.8 m3 / hr From Salmons general catalogue, required pump is, Model , 32-160-H1 (2poles - 50Hz, DN 50-32 )For Domestic Hot Water:

Model , 32-160-H1 (2poles - 50Hz, DN 50-32 )

Note: More details in Appendix C


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(3-5-5)Evacuated Tube Solar Collectors

The effective absorber area for (RS 01-15/1800) = 3.228 m2.

(x)= Oa1 (x)-a2 I(x)

2

(3-4)[17]

X=[Tm-Ta]/I] (3-5) [17]

O = Conversion Factor=(0.83)

T m = average inlet temperature (K).

T a = is the ambient temperature of the collector (K).

I = insolation level (Watts/m2

)

a1=Loss Coefficient: a1 = 1.14 W/(m2K)

a2 =Loss Coefficient: a2 = 0.0144 W/(m2K2)

For various ambient and insolation; efficiency will vary depending on these variables as seen from thelisted table:

Table (3-18 ):Solar energy

Month

Tavg

(C)

Q needed

(kW)

Energy/day

(kJ/day)

Solar

energy(I)

(kJ/m2

day)

Solar energy

(kcal/m2

day)col

Ecol.use

(kJ/m2

day)

May 22.6 54.00 2527283.3 24840 5932.9 83.0 20630

Jun 25.8 50.83 2378947.3 24120 5761.0 83.07 20036

Jul 27.4 49.25 2304779.2 24120 5761.0 83.11 20039

Aug 28.3 48.36 2263059.7 25920 6190.9 83.14 21538

From the table above we see that collector efficiency at May:

col = 83%


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102

The useful heat get from the collector given by the following equation:E col .use= col I

Where:

col : collector efficiency.

I: is the total solar insolation on the tilted collector (kJ/ m2 day).

E col .use: useful heat (kJ/m2 day)

In May: E col .use = 0.83 24840 = 20617.2 (kJ/m2 day). Collectors area could be found by dividing the total heat by the useful from

the collector;

A = Q tot / E col .use At May: A = (54360016)/ 20617.2 = 122.51m2 Number of collectors needed = A/3.228 Number of collectors =38

Optimization of evacuated tube solar collector:Collector area must be large enough to cover the load without the aid of

auxiliary system in the sunny days, but the optimum collector's area must meet the

economical requirements.

Knowing the collector area and the unit price, the collector cost could be found.

The total cost of the collector could be calculated as follows:

C col,(tot) = fixed cost + operating cost

C col,(tot) = FCR Investment + maintenance.

Where:

= + (1+

)

1 + + (3-6)


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103

Where:

i = interest rate = 10%

n = is the number of expected serving years of the system = 20 years.

t = annual taxes = 0

j = annual insurance = 0.3 %

FCR = 0.1 + [0.1 / {1 + 0.1)201}] + 0 + 0.003 = 11.6 %

This cost is calculated for different values of collector's area as shown below,

Then these values plotted against collector's area.

The breakeven point could be obtained from the figures and it shows the

optimum collectors area and its cost. Above this point the addition of solar

collectors will not be justified economically. As the collectors solar energy is

more expensive than fuel cost.

From the figurebelow breakeven point gives us

30 collectors of (RS 01-15/1800). With annual heating cost = 1692$/year

And the total collectors produced energy = 1654546.3 kJ / day

Figure (3-23): Cost optimizationfor evacuated tube solar collector


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air conditioning (ch3)

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