Abstract
This article reports on an experimental analysis and performance assessment of using thermoelectric generators (TEGs) for waste heat recovery from residential vapor compression refrigeration systems. The analysis shows that there is a good opportunity for waste heat recovery using TEGs by de-superheating refrigerant after the compressor. Design and manufacturing of a de-superheater unit consisting of a tube and plate heat exchanger and thermoelectric generator modules (HE-TEGs) have been performed and integrated in an experimental test rig of R134a refrigeration cycle. Experimental assessment of the performance parameters, as compared to the basic refrigeration system, reveals that the overall coefficient of performance (COP) using HE-TEGs desuperheater unit increases by values ranging from 17% to 32% depending on the condenser and evaporator loads. Exergy analysis shows that the enhancement is attributed to reduction in the exergy destruction in the condenser and compressor due to lower values of condenser pressure and pressure ratio of the compressor. The output power of the HE-TEGs unit is found to be sufficient for driving the TEGs heat sinks air cooling fan, thus providing a passive de-superheating system without an additional external source of electricity. Further enhancement of the refrigeration cycle performance can be achieved by installation of additional HE-TEGs units.
Highlights
Air conditioning and cooling systems consume more than 20% of the total electricity used in buildings around the world [1]
The vast bulk of air conditioning (AC) and refrigeration units in use today are based on vapor compression refrigeration system (VCRS) technology
The integration of heat energy storage with the VCRS can be used to overcome the mismatch in demand of hot water and cooling [4,5,6]
Summary
Air conditioning and cooling systems consume more than 20% of the total electricity used in buildings around the world [1]. The energy needed for space cooling is expected to triple by 2050 [1] This increase in cooling demand is putting an enormous load on electricity systems. A wide variety of air conditioning units are used including packaged or split; ducted or ductless; portable or stationary; small or large units. A split air conditioner consists of an outdoor condensing unit, where a large amount of heat is discharged to the atmosphere, and an indoor evaporator unit, where cooling is produced. The use of condensing heat of VCRS to provide domestic hot water for buildings could improve the system COP by about 38.6% [3]. The integration of heat energy storage with the VCRS can be used to overcome the mismatch in demand of hot water and cooling [4,5,6]
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