engleski

Heat Sources for the Heat Pumps

Highest significance for the heat pump installation has its heat source/sink. In other words, the heat pump system for heating application has higher efficiency if a heat source has better thermodynamic properties. Widely used low-temperature heat sources and heat sinks today are: water (river, lake, groundwater, or sea water), ground, air, or the Sun. To ensure efficient operation of the heat pump, heat source has to comply with a number of conditions, where the most important are: to provide the required heating capacity continuously at a higher temperature level ; connection between the heat pump and heat source should have the minimal possible costs ; energy use for the heat transfer between the evaporator and heat source should be the lowest possible. In this paper, basic characteristics of the different heat pump systems were analyzed, with emphasis on the solar - assisted heat pumps. In the thermal laboratory of the Faculty of Mechanical Engineering and Naval Architecture, the test system with the solar - assisted heat pump, using the direct expansion of the refrigerant in the unglazed solar collectors, was made. The results have shown that, in a region with a large number of hours with sunny weather conditions per year, e.g. the Croatian Adriatic coast, the system efficiency is very high. Coefficient of performance (COP) has moved within a range of 3 ÷ 7, sometimes even higher, depending on the outdoor weather conditions and the heat sink temperature (water temperature on the condenser outlet). At the same time, collector efficiency has moved within a range of 0, 6 ÷ 0, 9.

heat source; solar heat pump; COP

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