Studies on Solar Air Heating System with Waste Oils as Sensible Heat Storage Medium with a Focus on Energy Environmental Economic and Sustainability Aspects

Abstract

The intermittent nature of solar radiation poses a significant challenge to the widespread adoption of solar air heating collectors. Integrating thermal energy storage (TES) into these collectors can store excess heat for later use, addressing intermittent nature of solar radiation. Sensible heat storage (SHS) is a promising and economical approach for storing the thermal energy in solar air heating collectors. With approximately, 80% of the total SHS system cost attributed to storage tank and storage material. Reducing the cost of either component could significantly decrease the overall cost. Therefore, integrating an energy storage tank and exploring alternative could improve the economic viability. The growing demand for sustainable TES and commitment towards decarbonization necessitates the exploration of sustainable energy storage materials. Although synthetic mineral oils and vegetable oils have been proposed as SHSMs, their cradle-to-gate stage contributes to significant CO2 emissions and other environmental impacts, raising concerns about their overall sustainability. newlineThe objectives of the present work are to (i) find the thermophysical characteristics of waste car engine oil and servotherm medium oil (STM) and compare them for sensible heat storage application (ii) carry out the outdoor experiments with evacuated tube collectors (ETC) fitted with U-pipe heat exchangers to check the impact of the in-built energy storage medium (iii) validate the experimental results with numerical simulation (iv) analyze the thermal cycling stability of chosen waste oils -waste cooking oil (WCO), waste bike engine oil (WBEO), waste car engine oil (WCEO) and waste truck engine oil (WTEO) and rank them based on their thermophysical and chemical fingerprint stability, (v) estimate the economic, environmental and energy payback periods of U-pipe ETC with waste oil as SHSM (Up-WCEO-ETC) (vi) carry out the sustainability analysis of Up-WCEO-ETC and compare it with conventional fuels based air heating systems. newlineThermophysical.