Annual Performance Evaluation of Spiral Type Solar Water Heater Using Linear Regression Model

Abstract

The main challenges of designing a solar water heating system is the determination of the performance of the system for at least one year since solar radiation received from the sun varies from day to day and month to month. So most researchers are limited to testing their solar water heaters for a small period of time and use these test as basis for the performance. To be satisfied with any solar system it must be tested for at least a year. Thus, there is the need to have a realistic model that can predict the annual performance of the solar system considering all days of the year. A solar water heating system using flat plate collector was designed, constructed at the old site clinic of Bayero University, Kano. The system comprises of a collector and a storage tank, the collector has an area of 1.62m2. The spiral collector system was tested for 80 days (11 weeks) and performance data were recorded. This data was analysed to find the relationship between performance of the system and the solar radiation intercepted. An empirical model was then developed using the performance data collected for the spiral type solar water heating system. This empirical model can be used to predict the annual performance of the solar water heating system using weather data obtained from metrological centres. The model was found to accurately predict the system performance with a maximum weekly error of 11% and a total error based on the 11 weeks of data collected of 1.55 kWh/m2 corresponding to an error of 2.2%. It was also found out that the energy collected for a spiral type solar collector varies linearly with the solar radiation intercepted and the efficiency is independent on the solar radiation intercepted