CHAPTER 3 - WATER AND AIR HEATING APPLICATIONS

Abstract

Solar energy can be easily converted into heat and could provide a significant proportion of the domestic hot water and space heating demand in many countries. One of the drawbacks in high latitude countries is that there are many days in the winter months when the total radiation received will be too small to make any useful contribution. The most widely known and understood method for converting solar energy into heat is by the use of a flat plate collector for heating water, air or some other fluid. This chapter discusses various water and air heating applications. A solar collector constructed from two sheets of corrugated galvanized iron is installed in a conventional thermosyphon system. General conclusions regarding the solar collector, which are still very relevant are: (i) simplicity of the construction must be an essential feature of water and space heating, (ii) there is a considerable variation in the heat recovery rate, (iii) satisfactory heat collection efficiencies are only obtained where there is prolonged and intense direct radiation, and (iv) no direct correlation among sunshine hours. Solar air heaters have not attracted nearly as much research and development work as water heating systems. Air heaters have three particular advantages: (i) air cannot freeze, (ii) while air can leak, it is not nearly as serious as water leakage, and (iii) problems of corrosion in mixed metal systems and storage tanks are less likely.