Experimental investigation of refrigerator condensers for possible design improvements

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: NEJDET YİĞİT ÖZSAÇMACI

Danışman: HANİFE TUBA OKUTUCU ÖZYURT

Özet:

There is a continuous increase in the capacities of competitive markets in refrigeration industry. Meanwhile, new energy regulations for domestic appliances, including refrigerators become operative day by day. Hence, there is a strong requirement for improved performance of household refrigerators at reduced cost. The condenser is the main heat rejection component of the cooling cycle. The objective of this thesis is to conduct an experimental investigation for possible design improvements of wire-and-tube type refrigerator condensers. The experiments were held in the laboratories of Arçelik Refrigerator Plant in Eskişehir. In addition to standard performance tests, charge experiments, 43ºC tropical climate tests, and not door opening (NDO) experiments were performed. Temperature and pressure measurements were carried out with thermocouples and pressure transducers, respectively. The data collection was performed by a data acquisition system. The correlations for the refrigerant side heat transfer coefficients are obtained from the literature. Heat transfer rates are calculated with the help isobutane property tables and P-h diagram. Air side heat transfer coefficient is expressed in terms of convection only. Inside and outside convective heat transfer coefficients are calculated. The overall heat transfer coefficients are calculated and compared for different condenser configurations. Radiative effects are not considered in this study. In the scope of the thesis, three different sets of experiments have been conducted. In the first and the third sets, a test chamber has been used to investigate the effects of different condenser configurations on refrigerator energy consumption. In the second part of the study an experimental setup was used to investigate the performance characteristics of a variety of wire-and tube type refrigerator condensers. Experimental studies indicated that it is possible to save material and reduce the production cost by using shorter tubes of 4.76 mm diameter or tubes of 4 mm diameter without any loss in the thermal performance or increase in the energy consumption.