solar cooling - pelda › doc › report_sorptioncooling.pdf · 2015-10-23 · solar cooling...

solar coolingsustainable air conditioning for Barbados

Johannes Pelda ● Rasmus Borrmann

solar coolingJohannes Pelda ● Rasmus Borrmann

Solar CoolingAgenda

Introduction

Thermodynamic Basics

Sorption Chilling Processes

Project Approach

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INTRODUCTION

solar cooling – sustainable air conditioning for Barbados


BarbadosGeography

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Location: Carribean, North Atlantic Ocean, NE ofVenezuela

Area: 450 km²

Coastline: 97 km

Land use:arable land: 37.21% permanent crops: 2.33% other: 60.46%

Natural resources: petroleum, fish, natural gas


BarbadosPeople, Society, Economy

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Language: Englisch

Population: 283,733 inhabitants

Capital: Bridgetown (80,000 inhabitants)

GDP - official exchange rate: US$ 4.4 billion

GDP – composition by sector:agriculture: 3.4% (sugarcane, vegetables, cotton)industry: 13.4% (light manufacturing)services: 83.2% (tourism)

Unemployment rate: 12%

Public debt: 103.9% of GDP

Inflation rate: 7.4%


BarbadosClimate

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BarbadosEnergy Supply

Electricity production:

heavy fuel oil: 82%

diesel: 18%

fuel is imported – high degree of volatility in the market

extensive use of solar water heaters SWH

no domestic heating – solely hot water needed

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Spring Garden Generating Station: 51MW


BarbadosEnergy Supply

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Exchange Rates

1 BBD = 0.50 USD1 USD = 2 BBD

1 BBD = 0.38 EUR1 EUR = 2.60 BBD

Electricity Prices (400 kWh per month)

Barbados Light and Power109.26 EUR 1 kWh = 0.27 EUR

Stadtwerke Flensburg100.67 EUR1 kWh = 0.25 EUR

THERMODYNAMIC BASICS




Evaporative Cooling

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The Bādgir ofDowlat-abad in Yazd is one of thetallest airscoops

Fidel

Wind directionWind

Wind collector

Exhaust

Cooled cellar

Low pressure

Air flowFlowing water Chilling by convection and evaporation

Airflow into the Quanat

ground


• Puls transmission:Δ𝐺 𝑖 = 2𝑚𝑣𝑥𝑖

Thermodynamic BasicsEvaporative Cooling

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Not evaporating

Evaporating

Δ𝐺 𝑡 𝑜 𝑡𝑎 𝑙

∆ 𝑡< p ∙ A

Δ𝐺 𝑡 𝑜 𝑡𝑎 𝑙

∆ 𝑡> p ∙ A

Fidelmolecule

molecule

2𝑚 𝑣 𝑥 𝑖

Δ 𝑡

p ∙ A = F

molecule

p ∙ A = F

2𝑚 𝑣 𝑥 𝑖

Δ 𝑡


Thermodynamic BasicsWater Phases

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Water Phases

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The total pressureof a systemisgivenby𝑝𝑡𝑜𝑡𝑎𝑙 = 𝑝𝑤𝑎𝑡𝑒𝑟 + 𝑝𝑔𝑎𝑠

Thermodynamic BasicsWater Phases

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Pressure = F/A

Vacuum

Time = ∞video

../PA242191.AVI

SORPTION CHILLING PROCESSES



sorption chilling processessystem overview

thermal chilling

sorption chilling

open cycle

adsoption

absorption

closed cycle

adsorption

absorption

thermo-mechanical

chilling

Rankline-process

steam jet process

schukey motor

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open sorption chilling processesadsorption

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open sorption chilling processesabsorption

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closed sorption chilling processesadsorption

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closed sorption chilling processesabsorption

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sorption chilling processesannual electricity costs

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conventional chilling solar chilling

Office building size in m² 250

Refrigeration load in Wh/m²d 200

Refrigeration load of the office in kWh/a

18 250

Seasonal performance factor 5 - 6 10 - 13

Electricity needed in kWh/a 3650 1825

Electricity cost in Euros 1 254 561

PROJECT APPROACH



Project ApproachContacts

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Tom Rogers, PHDProfessorRenewable Energy Management

Prof Sir Hilary BecklesPrincipal UWI

Ruall HarrisFormer Permanent Secretary in the Ministry


Project ApproachSWOT Analysis

strengths

know-how

contacts

weaknesses

distance

opportunities

climate conditions

power price

threats

scale of technology

price

missing experts

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Project ApproachOutlook

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Status Quo

• James Husband (solar heater supplier)

• Tom Rogers (ambitious to support the project)

• Tony Gill (Hipac, company which is interested)

Next steps

• Design of a suitable cooling system (missing information from Hipac)

• More detailed ecomicalcalculation (details of the system configuration required)

Next semester

• Travel to Barbados

• Support of INEES funds

• Master Thesis UWI

Thanks for your attention!


Thermodynamic BasicsEquations

• Force:F = Δ𝐺𝑡𝑜𝑡𝑎𝑙

∆𝑡= p ∙ A

• Equationofstate:p = m ∙ 𝑅𝑠

𝑉∙ T

• Watervapourpressure:pwvp = f ∙ p sd= p(p s d = 31,7mbar (25°), f= relative airmoisture)

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Thermodynamic BasicsSaturation of Water Vapor

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closed sorption chilling processespros and cons

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open closed

adsorption absorption adsorption absorption

+ air conditioningpossible

+ low driving heat temperature

+ every heat useable


+ non-hazardous coolant

- size and weight

- contamination of sorbent

- no storage of coldness

+ air conditioningpossible


+ every heat useable

+ storage of coldness

- size and weight

- odor and material transmission

+ cold water

+ independent from ambient air humiditiy

- expensive

- lower COP

+ low temperature coldness possible

+ part load performance

- expensive

- danger of cristallisation

- ammoniac hazardous

CONVENTIONAL CHILLING



conventional chilling

06/06/2013 37

solar cooling - pelda › doc › report_sorptioncooling.pdf · 2015-10-23 · solar cooling...

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