Implementation of Thermal and Energy Improvements in Domestic Refrigeration: Case Studies

Background

In Mexico, refrigeration is responsible for approximately 30% of energy consumption in homes. According to the Trust for Electric Energy Savings (FIDE in Spanish), the refrigerator is the second appliance with the largest energy consumption. The potential for energy savings by replacing old inefficient refrigerators with highly efficient modern refrigerators, indicates savings of 4.7 TWh/year, which represents 33% of total annual consumption in the domestic refrigeration sector (Arroyo-Cabañas et al., 2009).

To put refrigerator usage into context, the average number of units manufactured annually in Mexico over the last four years for volumetric capacities up to 0.3 m³, was 1,500,000 units per year, and approximately twice the number of units for capacities greater than 0.3 m³ (INEGI, 2012). Without disregarding the undoubted increase in production, these numbers indicate that any improvement in the performance of refrigerators is very likely to achieve a great impact on energy savings. In addition, the electric power consumed by a domestic refrigerator is considered to be very costly, a reduction in the electricity consumption of a refrigerator could generate not only a competitive advantage for the manufacturer, but also in terms of the savings in overall energy use and a reduction of the total environmental impact of the product.

Several alternatives to improve the thermal-energy behavior identified in refrigerators have been reported in the scientific literature. These include for example, the use of nanoparticles in refrigerants and lubricating oils (Shengshan et al., 2008, Kwangho et al., 2009, Shengshan et al., 2011), which were found to induce interesting energy savings. The use of alternative refrigerants such as HFO1234yf, also projected improvements in energy performance up to 5% with simple modifications of the cycle (Bansal et al., 2011). Furthermore, thermal stratification in refrigerator compartments plays an important role in the quality of the stored products. Thus, panels have been installed with the phase change materials in the separate compartments to maintain steady temperatures (Gin et al., 2010; Oró et al., 2012). When panels are also placed next to principal components, they achieve a decrease in the number of working cycles of the compressor, and hence, a reduction in energy consumption (Marques et al., 2014; Wen-Long et al., 2011).