Development, Performance Investigation and Optimization of Solar Water Heater Hybridized with Conventional Fuel /

Abstract

Renewable energy resources utilization can address the both most emerging issues of the world in current era: rapid depletion of conventional fossil fuels reserves and drastic climate changes. The main theme of this work is analytical and experimental performance investigation of solar water heating (SWH) technology for Pakistan, a country facing disastrous power and gas shortfalls. For this purpose, a SWH system is designed for domestic sector of Pakistan using weather information of a location having latitude= 33.6oN and longitude= 73.1oE. Designed solar water heater in hybridized with conventional fuel using auxiliary fuel heater to provide backup for non-sunny time. Designed hybrid SWH system is modelled in TRNSYS simulation program using evacuated tube and flat plate collectors. Performance of hybrid evacuated tube solar water heating (ETSWH) system is evaluated and compared for winter season with gas water heating system. It is concluded that replacement of gas water heating system with hybrid ETSWH system would result in 23-42% seasonal natural gas fuel savings. Effect of water pipeline insulation and differential temperature controller presence is also investigated in terms of natural gas fuel savings. Performance of hybrid ETSWH system is compared with hybrid flat plate solar water heating (FPSWH) system and found that hybrid ETSWH system is much more efficient than FPSWH system. Comparative economic viability of hybrid ETSWH and hybrid FPSWH systems is analyzed in terms of net present value, internal rate of return, payback period and benefit-cost ratio. It is concluded that hybrid ETSWH system is more economical with ~5.7years payback period based on the savings achieved through reduced consumption of natural gas fuel. Environmental analysis is also performed in terms of greenhouse gases emissions reduction as result of hybrid SWH system application. Experimental setup mainly consists of heat pipe evacuated tube collector and multi-fuel furnace is developed and experimentation is performed providing natural gas as backup fuel. Percentage error between experimental and analytical results found equals to 5-6%. Performance of hybrid SWH system is optimized through MATLAB m-file mathematical modelling by determining the optimum tilt angle of south facing solar thermal collector, equals to Lat.+19o for winter season in capital city of Pakistan.