A comprehensive review on integrated collector-storage solar water heaters

Abstract

Conversion of solar energy to heat energy is a cost effective, sustainable and an efficient technology to heat water. Solar integrated collector-storage type of water heaters (ICSSWH) is a water heating device which alchemizes solar radiation directly into heat so that it is used for water heating. These systems are compact, simple in design and free from copper tubes bounded structures which unnecessarily causes heat losses and leakage issues. Their collection efficiency is usually higher than commonly used flat plate collectors (FPC). Despite of many advantages, the main disadvantage of compact integrated collection-storage type of water heaters (ICSSWH) is high heat losses during night hours which decreases the water affects the thus decreases the overall efficiency of the system. However, there are some strategies to minimize this heat loss from the system at the time when sunshine is not available; some of the methods are discussed in this paper. Moreover, in this article, the authors discuss the latest development in the new and improved compact water heater designs. In present paper authors critically reviewed various designs of ICSSWH. Use of insulated cover during night, introducing baffle plate structure, using PCM materials and using reverse thermosyphon valve are some of the strategies to minimize the heat losses from the system these methods are discussed in the present paper. Connecting tanks in series is also an effective method to overcome this problem of heat loss during night. In this paper the effect of connecting tanks in series on water temperature has been discussed. This paper presents an overall summary on compact ICSSWH systems which can be useful for further research to design and develop a new small size solar water heater.