Thermal performance of skin-type, hot-wall condensers, Part I: Component-level modeling and experimental evaluation

• Published in: International journal of refrigeration 2020-02, Vol.110, p.231-238
• Main Authors: Espíndola, Rodolfo S., Knabben, Fernando T., Melo, Cláudio, Hermes, Christian J.L.
• Format: Article
• Language: English
• Subjects: Aluminum; Compartments; Condenser; Condenser tubes; Condensers; Condensers (liquefiers); Condenseur; Contact resistance; Design parameters; Experimentation; Expérimentation; Foaming; Heat conductivity; Heat exchanger; Heat exchangers; Heat transfer; Household refrigerator; Mathematical models; Modelling; Modélisation; Peau; Performance evaluation; Polyethylenes; Refrigeration; Refrigerators; Réfrigérateur domestique; Skin; Temperature; Thermal conductivity; Thermal insulation; Échangeur de chaleur
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2019.11.010

•Novel mathematical model to predict the heat transfer rate of skin condensers.•Experimental validation with eigth hot-wall condenser designs.•Adhesive tape has the strongest impact on the heat exchanger performance. This paper comes out with an investigation of the thermal performance of skin-type hot-wall condensers for household refrigeration applications. Eight different hot-wall condensers were manufactured and installed in identical refrigerators. The condenser samples were constructed by varying the following design parameters: (i) adhesive tape (aluminum or polyethylene), (ii) tube O.D. (4.00 or 4.76 mm), (iii) total length (10 or 11.5 m) and (iv) condenser positioning. The refrigerators were placed inside a climate-controlled chamber and tested in steady-state conditions. A mathematical model that takes into account the heat transfer not only to the surroundings but also to the refrigerated compartments was also put forward. The model predictions were compared to the experimental data when deviations within the ±10% bounds were achieved. It was found that the adhesive tape thermal conductivity and the tube-outer sheet contact area have the strongest impact on the condenser performance. It was also found that the polyethylene tape increases the condensing pressure, due to its low thermal conductivity and thus to the smaller useful heat transfer area. It was thus concluded that the refrigerator foaming process must be carried out with an extreme care to avoid any negative impact on the tube-outer sheet contact resistance. Finally, it was noted that the heat transfer to the refrigerated compartments is directly affected by the condenser positioning and the thermal insulation thickness.