hot-wall condenser, domestic refrigerator, heat exchanger, energy consumption
This work focuses on the pros and cons of using hot-wall condensers in household refrigerators, based both in numerical and experimental approaches. To this end, eight different refrigerator samples of the same model were manufactured with distinct designs of hot-wall condensers. The design parameters were the following: (i) adhesive tape (aluminum or polyethylene), (ii) tube outer diameter (4 or 4.76 m), (iii) total length (10 or 11.5 m) and (iv) lay-out. An in-house mathematical model for hot-wall condensers was added to an in-house system simulation tool to predict the samples performance. Experiments were also conducted in a climate-controlled test chamber with each sample. Is has been found that the model predictions are close to the energy consumption measurements with deviations of the order of ±10%. It has also been found that the heat load is increased by 7.7% when a hot-wall condenser is added to the system. An extensive sensitivity analysis was also carried out, showing that the hot-wall condenser and thus the refrigerator performance is very much affected by the outer sheet thermal conductivity and thickness, but mainly by the tape thermal conductivity. The contact area between tape and outer sheet also plays a significant role in the heat transfer, meaning that a cheaper polymeric tape might be used if enough contact area is provided. Additionally, it has been found that there is always a tube pitch which minimizes the energy consumption in despite of the condenser geometry.