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Thermoelectric Heat Pump Geothermal Scale Model

Thermoelectric Heat Pump Geothermal Scale Model. E. Kimball Perley February 2013 ELM Senior Projects. What is Geothermal Heating?. Extracts heat from the ambient ground temperature Can be closed or open loop Can run off well water or an installed ground loop. Traditional Heat Pumps.

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Thermoelectric Heat Pump Geothermal Scale Model

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  1. Thermoelectric Heat Pump Geothermal Scale Model E. Kimball Perley February 2013 ELM Senior Projects

  2. What is Geothermal Heating? • Extracts heat from the ambient ground temperature • Can be closed or open loop • Can run off well water or an installed ground loop

  3. Traditional Heat Pumps Expansion Valve Evaporator Heat moves from the hot side to the cold side, this is Q Condenser Compressor The compressor is powered with electricity.

  4. Thermoelectric Modules • When a thermoelectic module is powered, it acts as a heat pump. • One side becomes warmer and the other cooler based on the polarity of the power. Heat moves from the hot side to the cold side, this is Q The module is powered with electricity. Hot Side Your Home Cold Side Ground Water

  5. Coefficient of Performance Q Heat Moved COP = Power into pump Electric Heat has a natural COP of 1 Traditional Geothermal has a COP of >1 Thermoelectric COP is dependent on the operating range

  6. The Advantages of Thermoelectrics • No moving parts • Ease of maintenance • Quiet • Scalable • Ease of Installation • Variable heat transfer

  7. Client Requirements • Table top scale model • Uses a thermoelectric heat pump • Takes heat from tap water at constant flow • Transfers heat to hot water tank • Maintains hot tank temperature at 100-110 Fahrenheit • Controls the power to the thermoelectric module

  8. System Diagram Laptop Water in Sensor Box T3 Flow regulator T4 Flow out Power Control Circuit Cold Thermoelectric Module T1 Aluminum Heat Spreader Hot Water Tank T2

  9. Software Design • The entire system will be controlled by a Lab View user interface. • The computer will both record all of the relevant data and calculate derived values such as power and COP • The user will need to input some data and turn the system on and off • The software will drive the module at a current dependent on the Dt of the system to increase performance. Laptop Sensor Box

  10. Mechanical Design • The system will use a module from HiZ • The max hot water tank size based on this module is 1 liter Water in T3 Flow regulator T4 Flow out Cold Thermoelectric Module T1 Aluminum Heat Spreader Hot Water Tank T2

  11. COP Requirements Max DT for COP > 1; 34 C Max DT for COP > 1 at 1.5 A 22C

  12. Sizing Calculations 20 Watts = 20 J/s 20 J/s * .238cal/J = 4.78 cal/s 4.78 cal/s * 3600 s/h = 17208 cal/h 20 Watts 17208 cal/h / 1000ml/l = 17C/h 8 Watts Moving 20 Watts of heat in an hour this module could raise the temperature of 1 liter of water by 17C.

  13. Electrical Design The National Instruments sensor box will power and read all four temperature sensors. It will also use 0-5 Volts to drive the power control circuit for the module. It will take readings of the power circuit to calculate the power being used. These readings are all necessary for the COP and other calculations done by the software. Sensor Box Power Control Circuit Thermoelectric Module T4 T2 T3 T1

  14. Power Control Circuit • A Power MOSFET transistor will control the flow of current through the Module. • Increasing the Voltage into the Gate of the MOSFET allows more current to flow, increasing the power to the Module Power Supply (25 Watts) Thermoelectric Module MOSFET D G 0-5v Signal from NI sensor box R Resistor S

  15. Budget Other components: Power supply NI USB 6008 Laptop Computer Flow controllers Micsleds, resistors, sensors, transistors, wiring

  16. Schedule

  17. Questions?

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