Study of Design Improvement and Evaluation Method of Integral-Type Solar Assisted Heat Pump Water Heater
Date Issued
2004
Date
2004
Author(s)
Lee, Ching-Po
DOI
zh-TW
Abstract
The conventional solar water heater can not be installed on rooftop and consumes a lot of electricity during cloudy or rainy days by backup heater. The integral-type solar-assisted heat pump water heater (ISAHP) was thus developed in the present study in order to improve the defects of conventional solar water heater. ISAHP absorbs ambient heat and solar radiation simultaneously. Four types of different ISAHP designs are proposed and studied. Experimental results show that ISAHP consumes about half electricity of the conventional solar water heater. The installation capacity is about 4.5 times of conventional solar water heaters.
To deal with the performance evaluation problem of ISAHP, the test method and test standard was studied. A semi-empirical model was derived from theoretical analysis and statistical analysis of test data. This model utilizes only the test data of ambient temperature, solar radiation, and water temperature in the storage tank to derive a correlation that can be used to evaluate the performance of various ISAHP designs. The test method requires to take 15 data points with the value of temperature difference between mean water temperature and average ambient temperature spread over evenly 5 to 15oC. The correlation will be not affected by seasonal effect from this criteria. The scattering effect of COP by the climatic variation will be reduced to minimal if a radiation ratio Rih for the first half and the last half test duration. A test standard is then suggested from this present study.
It is suggested that a ISAHP will pass its performance if COP is larger than 2.2 at Tf -Ta,ave=10oC.
For ISAHP to be utilized in foreign countries and for various ISAHP designs, the present study develops a computer simulation model for the performance analysis of ISAHP running at different weather conditions. The analysis provides important information for the design of ISAHP according to the location of application. The design analysis is used to investigate the performance of ISAHP at low ambient temperature and high solar radiation period.
Subjects
太陽能
熱泵
評估
solar
heat pump
evaluation
Type
thesis
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