Performance Evaluation of a Solar Domestic Hot Water Thermo syphon System for Gembu Taraba State, Nigeria

Abstract

The performance and economic feasibility of a solar water heating system in Gembu, Taraba state, Nigeria for the provision of hot water demand for domestic application was investigated. The study aimed to determine the effectiveness of  the system performance under different weather conditions, and the economic value. Here, the monthly average hot water loads required for domestic use at the location was first estimated as 60 liters per day at 55°C. Based on this demand, the required collector area was calculated using a flat plate collector efficiency of 40%. A TRNSYS model of the thermosyphon system was then developed to simulate thermosyphon system to assess its monthly average performance, considering variations between sunny and cloudy days. The performance of the model was validated through experimental data collected from January to April, with the accuracy measured using the mean average percentage error (MAPE). The findings revealed that 2.04 m² of collector aperture was suitable for most months. The system delivered hot water on the average at 40.15°C in August and 51.91°C in April, falling short of the desired 55°C which necessitated auxiliary heating in some months. The simulation model showed good agreement with the experimental data, with MAPE values ranging from 6.1% to 7.8%, indicating reliability. The system demonstrated a high annual solar fraction of 0.81, reflecting a good savings. The overall annual efficiency of the system was 34%. Economically, the system indicated an annual net saving of approximately 62% after accounting for auxiliary energy costs. The payback period for the system was found to be 7.6 years, with a positive net present value (NPV) of N1,439,319 after 20 years. The system offers significant economic benefits and contributes to environmental sustainability by reducing reliance on conventional energy sources. However, its performance varid with seasonal changes in solar radiation, leading to occasional shortfalls in meeting the desired temperature. Future work could focus on optimizing collector area design, improving auxiliary heating solutions, exploring energy storage options, conducting extended field test, and assessing the impact of technological advancements and fluctuating energy costs on the system's economic and environmental benefits. These steps could potentially enhance the system's reliability, efficiency, and overall feasibility, promoting wider adoption in different regions.