The Effect of Thermal Aging Polyurethane to Increasing the Energy Consumption of Refrigerator and Freezer
The role of the polyurethane is very important for energy consumption of refrigerator and freezers. The thermal conductivity of the polyurethane has been taken into account when designing the refrigerator and freezers (R/Fs). Since the diffusion process h
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The Effect of Thermal Aging Polyurethane to Increasing the Energy Consumption of Refrigerator and Freezer Fatih Ozkadi Arcelik A.S. R&D Center, Turkey
Abstract. The role of the polyurethane is very important for energy consumption of refrigerator and freezers. The thermal conductivity of the polyurethane has been taken into account when designing the refrigerator and freezers (R/Fs). Since the diffusion process has occurred inside the cells of the polyurethane the thermal conductivity has been increased by the time. This results in increasing heat gain of the cabinet and increasing energy consumption ofR/Fs.
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Introduction
As known energy consumption of refrigerator and freezers has been labeled in Europe and US. When labeling energy consumption value, initial energy consumption test results have been used. These products are being stored as a certain of time after the production. Because of the thermal aging of the polyurethane, energy consumption of those has been increased in this storage period. Sometimes R/Fs has been taken from market, then their energy consumption value has been checked by some consumer organizations. Increase in energy consumption can be important in this manner. Information about the thermal aging of polyurethane foam has been given in some papers. A good prediction model was explained as follows: The k-value for 50% cPentane/C02 gas mixture increases from 13 mW/m.K to 20 mW/m.K after 20 years of aging, or an increase of 53% [I]. The 25-year aged thermal conductivity values were found to correspond to the formula for HCFC-14Ib blown products of (k 1+6.7) mW/m.K (where k1 = initial thermal conductivity) and for n-Pentane blown products of (k l +5.4) mW/m.K; the comparable formula for CFC blown products was found to be (k.+6.5) mW/m.K [2]. The mixture of some blowing agents was investigated on thermal aging [3]. Polyurethane supplier companies have started to present new foam systems, which have good thermal aging characteristic [4]. Nevertheless there is limited information and test results on heat gain aging and increasing energy consumption for R/Fs in the literature.
P. Bertoldi et al. (eds.) , Energy Efficiency in Househould Appliances and Lighting © Springer-Verlag Berlin · Heidelberg 2001
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The following parameters should be taken care for increasing energy consumption of RlFs by the time: • • • •
Increasing thermal conductivity of polyurethane Decreasing the sealing properties of gaskets Decreasing heat transfer coefficient of condenser because of dusts occurred Increasing or decreasing COP (Coefficient of Performance) value of compressor because of changing the mechanical efficiency by running parts inside the compressor
Since among these effecting parameters dominant one is mostly increasing thermal conductivity of polyurethane, this topic is discussed as detailed in this paper. In this study a number of polyurethane, which were blown by c-Pentane from different suppliers, were examined and the thermal aging test data by measuring the thermal conductivity has been obtai
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