Year-round and techno-economic feasibility analyses on integration of absorption based mobile thermochemical energy storage with building cooling system in tropical climate

Abstract

In recent years, growth in urbanization resulted in increased global energy demand. It is projected that by 2050, 45% of overall energy demand is through air conditioning/building space cooling applications. To meet the above-mentioned energy demand, there is a need for thermal energy management of the cooling system by utilizing waste heat from the industries. Thus, mobile/portable thermochemical energy storage (MTES) came into existence to utilize waste heat for building space cooling applications. In the present investigation, a case study on year-round and techno-economic feasibility of MTES system in district energy network, by extracting waste heat from Rourkela Steel Plant and transporting it to the NIT Rourkela academic building space cooling system is analyzed by developing a thermal model. For this case study, the capacity of the cooling system, the distance between the steel plant to the admin building, steam temperature through which thermal energy is generated and mass flow rate of steam are chosen as 1055 kW (300 Ton of Refrigeration), 7.4 km, 500 °C, and 25 tons/hr., respectively. Lithium Chloride is taken as molecular/thermochemical energy storage material or liquid desiccant. The required quantity of absorption material for each trip, no. of trips between the plant and building per day, device storage capacity, amount of heat dissipated to the surroundings for each trip, and location of the waste heat utilization unit in the steel plant are taken as techno-economic evaluation parameters. Then, MTES system performance and techno-economic feasibility studies for the year 2020 is carried out in accordance with the tropical climatic conditions of Rourkela, India. From this analysis, it is observed that during peak sunny day, heat dissipation from charging station to discharging station is about 927.24 MJ whereas from discharging station to charging station is about 145.76 MJ. The energy and round-trip efficiencies ratio which are the ratio of useful cooling output to the waste heat input and the ratio of heat dissipated to the surroundings during transit from charging station to discharging station to the waste heat provided at the charging station are observed to be 4.51 and 52%, respectively. Moreover, to make the system more economic and dependent upon renewable sources, the efficacy and profit incurred by diesel trucks, solar-powered trucks, and hybrid trucks are also assessed and compared in detail.