A novel Integrated Collector Storage Solar Water Heating (ICSSWH) prototype: experimental investigation and simulation model

This paper reports the design and performance analysis of a novel Integrated Collector Storage Solar Water Heater (ICSSWH). Existing ICSSWHs are typically simple and low-cost devices that combine heat collection and storage functions in one unified vessel. However, during non-collection periods they are affected by higher heat loss characteristics when compared to standard solar collector systems. The unique presented ICSSWH prototype, developed at the Centre for Sustainable Technologies (CST) at Ulster University, is the enhancement of heat retention during non-collection periods. Using a novel thermal diode feature, achieved by incorporating a liquid-vapour phase change material (PCM) and very low pressures, heat retention values of approximately 60% are achievable. In addition, the concept aims to deliver low manufacturing costs through cost-effective materials and simple design solutions. In order to investigate the energy performance of the prototype under different boundary and working conditions, a suitably dynamic simulation model has been developed and implemented in a computer code written in MatLab environment. The developed model has been validated by means of experimental data gathered during indoor testing carried out under the solar simulator facility at the Ulster University laboratory. Specifically, all the modelled temperatures are ± 1°C from the respective experimental measurements, with corresponding average percentage errors of 0.92%, 1.38% and 1.64% for the main collector surfaces temperatures. Furthermore, a prototype comparison tool is implemented in order to optimize the collector performance in relation to several parameters (e.g. components, geometry, operating condition, etc.) and prove the potential of the developed software to optimise the proposed prototype. From the carried out comparison, the ICSSWHs prototype is characterized by higher temperatures (4 and 7 °C after 6 and 14 hours in retention mode) vs. simpler collector typologies. Applying the ICSSWH to provide domestic hot water to a single dwelling unit, performance modelling can be used simulate unit performance for different weather zones and usage profiles thereby optimising physical features and materials to improve energy, economic and environmental perspectives.