Solar water heating system

Abstract

Solar water heating system is one of the earliest uses of solar energy in human life, which enjoy many advantages, such as mature technology, simple structure, and low cost. Nowadays, solar water heating system is not only used for the domestic water heating project, but also used in the field of high technical requirements such as heating, air conditioning, industrial water, and swimming pool heating. In this chapter, the split-type vacuum tube water heating system and split-type flat plate water heating system were structured. Afterward, an analysis regarding their performance was conducted. The research results showed that the reverse slope has great impact on the thermal performance of the split-type vacuum tube solar water heating system, such as that the stratification of the water tank decreased by 3% and the collecting thermal efficiency decreased by 15% d from 60% to 45%. Under the 90° installation angle, the average daily thermal efficiency of the horizontal vacuum tube solar collector is 25% higher than the thermal efficiency of the vertical vacuum tube solar collector. The efficiencies of the horizontal flat plate collector and vertical flat plate are 28% and 19.8%, respectively. When the flat plate solar water heating system is circled by water circulating pump, the growth rate for the system thermal efficiency was 13%. Moreover, the height of the bottom of the water tank to the top of the collector has limited impact on the system thermal efficiency. When the height between the water tank bottom and the collector top varied between 0.44 m and 1.04 m, the range of the thermal efficiency is less than 3%. Finally, the operation performance of the hot water heating system compounded by solar water heater and air source heat pump applied in cold Tibetan area of Shangri-La was tested by experiment. The result revealed that when the outdoor environment temperature is 7° C, 2 °C, and 7 °C, capering with the independent heat pump heating system, the heat production and of the hot water heating system compounded by solar water heater and air source heat pump improved 16.2%, 14.1%, and 11.5%, respectively, while the system COP increased 19.0%, 10.6%, and 5.5%, respectively.