An Evaluation of the Solar Thermal Performance of the Solar/Geo Thermal Hybrid Hot Water System for a Detached House

Title & Authors
An Evaluation of the Solar Thermal Performance of the Solar/Geo Thermal Hybrid Hot Water System for a Detached House
Baek, Namchoon; Han, Seunghyun; Lee, Wang Je; Shin, Ucheul;

Abstract
In this study, an analysis was performed on the performance of the solar water heating system with geo-thermal heat pump for a detached house. This system has a flat plate solar collector ($\small{8\;m^2}$) and a 3 RT heat pump. The heat pump acts as an auxiliary heater of the solar water heating system. These systems were installed at four individual houses with the same area of $\small{100\;m^2}$. The monitoring results for one year are as follows. (1) The average daily operating time of the solar system appeared to be 313 minutes in spring (intermediate season), and 135 minutes and 76 minutes in winter and summer respectively. The reason for the short operating time in summer is the high storage temperature due to low water heating load. The high storage temperature is caused by a decrease in collecting efficiency as well as by overheating. (2) The geothermal heat pump as an auxiliary heater mainly operates on days of poor insolation during the winter season. (3) Despite controlling for total house area, hot water consumption varies greatly according to the number of people in the family, hot water usage habits, etc. (4) The yearly solar fraction was 69.8 to 91.5 percent, which exceeds the maximum value of 80% as recommended by ASHRAE. So the solar collector area of $\small{8\;m^2}$ appeared to be somewhat greater for the house with an area of $\small{100\;m^2}$. (5) The observed annual efficiency of solar systems was relatively low at 13.5 to 23.6%, which was analyzed to be due to the decrease in thermal efficiency and the overheating caused by a high solar fraction.
Keywords
Solar thermal system;Ground source heat pump;Solar fraction;Solar hot water system;
Language
Korean
Cited by
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