Thermoelectric temperature control

Thermoelectric temperature control is the use of the thermoelectric effect, specifically the Peltier effect, to heat or cool materials by applying an electrical current across them. ^[1] A typical Peltier cell absorbs heat on one side and produces heat on the other. ^[1] Because of this, Peltier cells can be used for temperature control. ^[1] However, the currently use of this effect for air conditioning on a large scale (for homes or commercial buildings) is rare due to its low efficiency and high cost relative to other options. ^[1]

Figure 1. Energy balance of a Peltier cell based heat pump

Peltier cell heat pump

A typical Peltier cell based heat pump can be used by coupling the thermoelectric generators with photovoltaic air cooled panels as defined in the PhD thesis of Alexandra Thedeby. ^[2] Considering the system with an air plant that ensures the possibility of heating on one side and cooling on the other. ^[3] By changing the configuration it allows both winter and summer acclimatization. ^[4] These elements are expected to be an effective element for zero-energy buildings, if coupled with solar thermal energy and photovoltaic ^[5] with particular reference to create radiant heat pumps on the walls of a building. ^[6]

It must be remarked that this acclimatization method ensures the ideal efficiency during summer cooling if coupled with a photovoltaic generator. The air circulation could be also used for cooling the temperature of PV modules.

The most important engineering requirement is the accurate design of heat sinks ^[7] to optimize the heat exchange and minimize the fluiddynamic losses.

Thermodynamic parameters

The efficiency can be determined by the following relation:

${\displaystyle \eta ={\frac {T_{C}-T_{H}}{T_{C}}}}$

where ${\displaystyle T_{C}}$ is the temperature of the cooling surface and ${\displaystyle T_{H}}$ is the temperature of the heating surface.

The key energy phenomena and the reason of defining a specific use of thermoelectric elements (Figure 1) as heat pump resides in the energy fluxes that those elements allow realizing: ^{[8] [9]}

• Conductive power ${\displaystyle {\dot {Q}}_{L}}$: ${\displaystyle {\dot {Q}}_{L}={\frac {L}{d}}S(T_{H}-T_{C})}$
• Heat flux on the cold side ${\displaystyle {\dot {Q}}_{C}}$: ${\displaystyle {\dot {Q}}_{C}=\alpha IT_{C}-{\frac {I^{2}R}{2}}-{\frac {k}{d}}A\Delta T}$
• Heat flux on the hot side ${\displaystyle {\dot {Q}}_{H}}$: ${\displaystyle {\dot {Q}}_{H}=\alpha IT_{C}+{\frac {I^{2}R}{2}}-{\frac {k}{d}}S\Delta T}$
• Electric power ${\displaystyle {\dot {E}}_{EL}}$: ${\displaystyle {\dot {E}}_{EL}=\alpha IT_{C}+I^{2}R}$

Where the following terms are used: ${\displaystyle \Delta T=T_{H}-T_{C}}$, ${\displaystyle I}$ electric current; α Seebeck coefficient; R electric resistance, S surface area, d cell thickness, and k thermal conductivity.

The efficiencies of the system are:

1. Cooling efficiency: ${\displaystyle \eta _{C}={\frac {\dot {Q_{C}}}{{\dot {E}}_{EL}}}}$
2. Heating efficiency: ${\displaystyle \eta _{H}={\frac {\dot {Q_{H}}}{{\dot {E}}_{EL}}}}$

COP can be calculated according to Cannistraro. ^[10]

Final uses

Thermoelectric heat pumps can be easily used for both local acclimatization for removing local discomfort situations. ^[11] For example, thermoelectric ceilings are today in an advanced research stage ^[12] with the aim of increasing indoor comfort conditions according to Fanger, ^[13] such as the ones that may appear in presence of large glassed surfaces, and for small building acclimatization if coupled with solar systems. ^{[14] [15]}

Those systems have the key importance in the direction of new zero emissions passive building because of a very high COP value ^[16] and the following high performances by an accurate exergy optimization of the system. ^[17]

At industrial level thermoelectric acclimatization appliances are actually under development ^[18]

References

1. L. E. (2008). Cooling, heating, generating power, and recovering waste heat with thermoelectric systems. Science, 321(5895), 1457-1461. http://engin1000.pbworks.com/f/TE_rev.pdf
2. Alexandra Thedeby, Heating and Cooling with Solar Powered Peltier Elements, Ms. Thesis, Department of Energy Planning, Division of Efficient Energy Systems, Faculty of Engineering, Lund University http://www.ees.energy.lth.se/fileadmin/ees/Publikationer/2014/Ex5308-AlexandraThedeby-HeatingAndCoolingWithSolarPoweredPeltierElements....pdf
3. Martín-Gómez, C., Ibáñez-Puy, M., Bermejo-Busto, J., Sacristán Fernández, J. A., Ramos, J. C., & Rivas, A. (2016). Thermoelectric cooling heating unit prototype. Building Services Engineering Research and Technology, 37(4), 431-449.
4. Yilmazoglu, M. Z. (2016). Experimental and numerical investigation of a prototype thermoelectric heating and cooling unit. Energy and Buildings, 113, 51-60.
5. Liu, Z., Zhang, L., Gong, G., Li, H., & Tang, G. (2015). Review of solar thermoelectric cooling technologies for use in zero energy buildings. Energy and Buildings, 102, 207-216.
6. Khire, R. A., Messac, A., & Van Dessel, S. (2005). Design of thermoelectric heat pump unit for active building envelope systems. International Journal of Heat and Mass Transfer, 48(19-20), 4028-4040. https://messac.expressions.syr.edu/wp-content/uploads/2012/05/Messac_2005_JHMT_ABE.pdf
7. Trancossi, M., Pascoa, J. (2020). Design of ventilated cross flow heat sinks. Modelling, Measurement and Control C, Vol. 79, No. 3, pp. 90-97. https://doi.org/10.18280/mmc_c.790305
8. Jugsujinda, S., Voraud, A., & Seetawan, T. (2011). Analyzing of thermoelectric refrigerator performance. Procedia Engineering, 8, 154-159. https://www.researchgate.net/publication/251716178_Analyzing_of_Thermoelectric_Refrigerator_Performance
9. Goldsmid, H. J. (2016). Theory of Thermoelectric Refrigeration and Generation. In Introduction to Thermoelectricity (pp. 9-24). Springer, Berlin, Heidelberg.
10. Cannistraro M. and Trancossi M., (2018) Indoor comfort in presence radiant exchanges with insolated glassed walls and local acclimatization to increase indoor comfort conditions, Italian Journal of Engineering Science: Tecnica Italiana, Vol. 61+1, pp. 27-35.
11. Cannistraro G, Cannistraro M, Restivo R. (2015). The local media radiant temperature for the calculation of comfort in areas characterized by radiant surfaces. IJHT 33: 115-122. http://iieta.org/sites/default/files/Journals/IJHT/33.2_13.pdf
12. Lertsatitthanakorn, C., Wiset, L., & Atthajariyakul, S. (2009). Evaluation of the thermal comfort of a thermoelectric ceiling cooling panel (TE-CCP) system. Journal of electronic materials, 38(7), 1472-1477.
13. P.O. Fanger, Thermal Comfort Analysis and Application in Environmental Engineering (New York: McGraw-Hill, 1972) https://www.cabdirect.org/cabdirect/abstract/19722700268
14. Le Pierrès N, Cosnier M, Luo L, Fraisse G. (2008).Coupling of thermoelectric modules with a photovoltaic panel for air pre‐heating and pre‐cooling application; an annual simulation. International Journal of Energy Research 32(14): 1316-1328.
15. Trancossi M., Kay J., Cannistraro M., (2018) Peltier cells based acclimatization system for a container passive building, Italian Journal of Engineering Science: Tecnica Italiana Vol. 61+1, No. 2, December, 2018, pp. 90-96 http://iieta.org/sites/default/files/Journals/IJES/61+1.02_06.pdf
16. Zhang, X., & Zhao, L. D. (2015). Thermoelectric materials: Energy conversion between heat and electricity. Journal of Materiomics, 1(2), 92-105.
17. Trancossi, M., Cannistraro, G., & Pascoa, J. (2020). Thermoelectric and solar heat pump use toward self sufficient buildings: The case of a container house. Thermal Science and Engineering Progress, 18, 100509. https://www.researchgate.net/publication/339429358_Thermoelectric_and_solar_heat_pump_use_toward_self_sufficient_buildings_The_case_of_a_container_house
18. Marlow - PRIMARY USES FOR THERMOELECTRIC MODULES https://www.marlow.com/resources/thermoelectric-technology-guide/ii-tem-primary-uses