Effect of hot water load patterns on the design parameters of thermosyphon solar water heaters

This paper attempts to demonstrate the effect of hot water load pattern on the design parameters of the thermosyphon solar water heaters. An accurate design tool for sizing and optimising thermosyphon solar water heaters based on TRNSYS simulation program is used. Three different load patterns with the same volume of consumption morning, evening and all day simple load patterns are considered to see their effect on the design parameters of the solar systems. The study has shown that, there is an important effect of the load pattern on the system size and cost. For the same quantity of hot water withdrawn (180 litres) from the system at the same load temperature 60°C, the morning load requires a bigger system and then of course a more costly than the other load patterns. The most affected of the design parameters is the tank volume, a relatively bigger tank volume being required for the morning and the evening load patterns than the all day simple load pattern. This could be attributed to the fact that in the morning or evening periods, a bigger tank volume is required to benefit from the whole period of sunshine, in that enough water can be heated up and thus kept for the later period of use.