OGZEB Hybrid Thermal Electrical Energy Storage System

Midterm 2 Presentation

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Team members: Corey Allen, Anthony Cappetto, Lucas Dos Santos, Kristian Hogue, Nicholas Kraft, Tristian Jones, Artur Nascimento

Sponsors/Advisors: Dr. Li, Dr. Ordonez, Dr. Zheng

Date: 11-21-2013

Artur Nascimento

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Outline

• Midterm 1 Recap• Battery Array Progress• Overview of Thermal Storage System• Tentative Procurement Options• Future Plans • Conclusion• Questions

Artur Nascimento

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Midterm 1 Recap

• Design energy storage system for the OGZEB• System must store excess power generated by

the house’s solar cells to be used at night• System will consist of an array of batteries and

a thermal energy storage device

Artur Nascimento

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Midterm 1 Recap

• Objective 1: Develop a model of the house’s power needs to determine the best type, number, and arrangement of batteries for the house

• Objective 2: Create a cold reservoir to store thermal energy

Artur Nascimento

Corey Allen 5

Battery Selection

• Group was unable to get the proper load data we needed from the house due to technical issues.

• After talking to Thomas (sponsor), we were able to make the following assumptions about the house

1. The maximum peak load for the house is 5 kwh2. This peak load will occur during the summer3. Using previous load data from a similar house we could create

a general model for the load of the OGZEB house4. Ideally, the batteries should be able to power the house for 24

hours. This minimum requirement was set by Dr. Ordonez

Corey Allen 6

OGZEB load analysis

• The AC system consumes the most energy

• Peak Load: 5kwh

• Average Load: 1.9kwh

• Avg. Load per day: 46kwh

Winter FallSummerSpring

Corey Allen 7

Battery SelectionBattery Type Dimensions

(L x W xH) (mm)

Weight (kg)

Voltage Amp-Hours

(@ 20 hr)

Lifetime Cost(per

battery)

Trojan T-105 264 x 181 x 276 28 6 225 3 - 6 years $140

Trojan L16H 296 x 176 x 425 57 6 435 6 - 8 years $315

Surrette 4-CS-25PS

559 x 286 x 464 115 6 820 12-15 years $1,337

Trojan T-105 Trojan L16H

8 in series 48 Volts 225 A-hr

8 in series 48 Volts 225 A-hr

8 in series 48 Volts 435 A-hr

Final Analysis

Battery # of battery Initial Power

Total Price

T-105 16 21.8 kwh $2240

L16H 8 20.8 kwh $2520

Tristian Jones 8

Thermal Storage Designs

Tristian Jones 9

Initial Design• Chiller cools water during the day• Cold water is pumped into coils to exchange heat with the air into the house• Arrangement is relatively compact and common in existing systems• Requires the use of a pump and fan at night, reducing power savings• Risk of damaging pump with shards of ice

Chiller

Glycol In

Glycol Out

Water Tank

Water Pump

Fan and Heat Exchanger

Water in

Water Out

Air outAir in

Tristian Jones 10

Refined Design Concept

• Chiller cools water during the day• Water cooled inside of tanks• Tanks are designed to maximize heat transfer

when air is drawn past them• Air run directly over tanks into the house• Removes pump from previous design

Tristian Jones 11

Refined Design Visualization

Chiller

Warm Glycol Out

Finned Water Tanks (3)

Air In Air OutCold Glycol Into Box

Battery Container

Cool Air in

Tristian Jones 12

Cold Storage Box and Heat Exchanger

Hot air in Cold air out

Cold Glycol from Chiller

Warm Glycol to Chiller

Water Tanks

Fins

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Battery Temp Regulation

Battery Container

ValveTemperature Sensor and valve actuator

Cold Air from system used to cool batteries

Kristian Hogue

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Battery Temp Regulation

Thermal Battery Management Specifications- Arduino Uno Project Board

- 14 Digital outputs/inputs- 6 of 14 are Digital PWM

- 6 analog input pins - This board will be programed to control the valves into the battery boxes

Kristian Hogue

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Other items

Kristian Hogue

- LCD screen to display the temperature

- 2 Stepper motors to control the valves

- Thermostat or Thermistor to observe the temperature of the box

Tristian Jones 16

Additional Components

• Chiller and fan to be purchased according to specs

• Current design utilizes a 0.68 ton chiller and 870 cfm fan

• Secondhand products may be available (Recycled products are a plus for the OGZEB)

• Lumber and insulation can be bought from local hardware stores

• Aluminum for water tanks available online

Tristian Jones 17

Additional Design Aspects

• Outside of air exchange box to be insulated with roofing insulation, to minimize heat transfer to environment

• Inside of wooden air exchange box to be painted with anti-mold and mildew paint

• Air exchange box to have drain to remove condensation

• If batteries begin to overheat, valve opens to allow cold air from the system to cool the batteries

Tristian Jones 18

Design Evaluation

• Removes pump from previous design, resulting in greater system efficiency

• Provides for a variety of design features such as battery temperature regulation

• Addresses the home’s primary energy usage: air conditioning

• Is bulky compared to the initial design– Air exchange box alone is currently 2 x 3.4 x 7.8 ft

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Ice Melt Analysis• For the analysis of the fin heat transfer, the assumption of an adiabatic fin tip was made due to the

fin tip being up against the inside surface of the wood box. • Assumed ambient temperature of 20 C and ice temperature of 0 C.• Water latent heat of fusion = 334 kJ/kg• Total heat loss required to melt 400 L ice = 133.6 MJ• The heat loss rate through the NON-FINNED area of 3.13 square meters will be approximately

838W.• The total heat transfer for a fin (adiabatic tip) is given by:

• The total heat transfer for a single aluminum fin was found to be 40.5 W.• If the total heat transfer for a single fin is multiplied by the number of fins (48 total), a total fin

heat transfer rate can be calculated to be 1942 W.• If both the non-finned surface heat transfer and finned heat transfer are added together the

combined total heat transfer (H) can be calculated to be 2780 W.• Finally, the melting time can be calculated:

Artur Nascimento

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Procurement (Thermal)Part Supplier Cost NotesChiller Mokon $5920 New (1 ton)

Ebay $1250 - 2550 Used, cosmetically unappealing (0.68 ton)

Fan Grainger $260 870 cfm

Boxes Home Depot $2.8 / sq. ft. Weldable Aluminum

Storm $18 / sq. ft. Copper Sheet

Wood Home Depot $0.85 / sq. ft. plywood

Home Depot $2.50 / board Board 2” x 4” x 8’

Insulation Home Depot $12 / pack Fiberglass (roofing) 9.5” x 15” x 25’

Tubing Grainger $2.50 / ft. Refrigeration coil 3/4” OD

Home Depot $2.90 / ft. Soft Copper Utility Coil

Home Depot $1.40 / ft. Copper Utility Coil

Total Estimated Cost $2400 Material only, does not include regulatory electronics,

only for thermal system

Artur Nascimento

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Conclusion

• Battery type, number, arrangement and supplier have been determined

• Thermal Energy Storage System design concept complete

• Suppliers and parts located

Artur Nascimento

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Future Plans

• Continue analysis of proposed thermal system– Investigate potential for compacting system

• Order materials• Install battery array• Begin design of energy management system

and housing integration• Evaluate potential of adapting system to work

during the winter, when AC use is unnecessary

Artur Nascimento

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Questions