Refrigerant-charged integrated solar water heater

Abstract

The performance of two R‐11‐charged integrated solar water heater collectors was investigated experimentally for forced and natural circulation water flows. The heat transfer from the refrigerant loop to the hot water storage tank took place through a condenser of novel design integrated within the collector frame. The effect of the condenser inclination on the system efficiency was remarkable for natural circulation water flow but had no significant effect for forced circulation flow. The difference in thermal response between the refrigerant and water loops caused buildup of stored energy in the condenser. This energy affected the buoyancy forces and generated flow pulsation that caused a harmonic‐like variation of the system efficiency. This effect vanished with forced water circulation flow. The system efficiency varied between 20 and 50% depending on the solar insolation.

Experimental study of a refrigerant charged solar collector

“…The heat loss ratio is Figure 9 (continued) indicative of the type of bond between plate and pipe and is not very low. However, the system efficiency against heat loss ratio curve correlates with data already gathered by Radhwan et al (1990). Figure 12 indicates the average heat transferred by each heat pipe during the test run to the system.…”

“…This oscillating flow in well illustrated in Figure 8. In a series of experiments conducted in Saudi Arabia by Radhwan et al (1990) report likewise that the difference in thermal response between R11 and water loops caused a build up of stored energy in their condenser. This energy affected buoyancy forces and generated flow pulsation, with very little circulating flow.…”

A preliminary experimental investigation on characteristics of natural convection based on solar thermal collection using supercritical carbon dioxide

“…Solar water heater is one of the most promising low-temperature solar thermal systems [1][2][3][4][5][6][7]. During recent years, a lot of studies have been carried out in the field of solar water heater and low-temperature solar thermal convection [8][9][10][11][12][13][14][15][16], which are mainly for the solar water heaters of water-in-glass evacuated tube type [17,18].…”