Studies on the performance of natural circulation forced circulation and wind assisted domestic solar hot water systems

Abstract

Domestic Solar Hot Water Systems are gaining wide acceptance because of increased focus on renewable energy use and CO2 emission reduction More than 90 of domestic hot water systems in use are of Natural Circulation type because of its simplicity Larger size solar hot water systems operate in Forced Circulation mode which employs an electrically driven pump In general thermal efficiency of natural circulation system is lower than the forced circulation system In the present investigation a wind mill driven pump is added in the existing natural circulation loop Whenever wind flow is available the wind driven pump provides additional circulation to the natural circulation which is expected to improve the efficiency of the system An experimental investigation is carried out to study the performance of a 200 litre capacity domestic solar hot water system in Natural Circulation Forced Circulation and Wind mill driven modes The facility has two liquid flat plate solar collectors each of 2 0 m2 collector area an insulated storage tank connecting pipes non return valve and necessary instrumentation A 250 W electrically operated pump is used during forced circulation mode