Feasibility Study on Energy Saving Scenarios of Preinstalled Vapour Compression Chiller Based District Cooling System

Abstract

This study aims to assess the feasibility of various energy saving strategies for an existing district cooling system (DCS) that works on vapour compression chillers with a total of 680 TR capacity, located inside the campus of the academic institute, NIT Rourkela. The DCS supplies chilled water for cooling to multiple buildings of the institute. To improve the performance of this existing district cooling system, five alternative energy saving scenarios are considered along with the base case scenario. The first scenario considers supplying the chilled water from central source to hostel buildings during night time or weekends when chiller is not operational in academic buildings (i.e., non-office hours) (Case–I); the second scenario employs solar panels to run the compressors of the two existing vapour compression chillers. (Case–II); the third scenario considers storage of waste heat rejected from the condenser for district heating purpose during winter season. (Case–III); the fourth scenario considers circulation of chilled water during non-working hours in seasonal thermal energy storage device for utilizing in peak demand conditions/situations (Case–IV) and the fifth scenario considers water conservation from mechanical draft cooling towers of vapour compression chiller based DSC (Case–V). The feasibility assessment parameters chosen for Case–I is cooling load demand of the hostel building, Case–II is number of solar panels and peak power load demand of DCS, Case–III is waste heat energy storage capacity during office hours per day, Case–IV is chilled water thermal energy storage capacity during peak load demand and Case–V is conserved water capacity from cooling tower. Based on feasibility assessment parameters, it is understood that in Case – I, one third cooling capacity of chiller is effectively utilized for cooling a hostel during non-working hours and weekends, In Case–II, 3084 solar panels are required for running the compressor of 680 TR capacity, In Case–III, waste heat captured is 1450 kW capacity per day, In Case-IV, about 1,190 kW capacity of chilled water energy storage has been occurred for three hours whereas in Case–V, from cooling towers, 1652 litre per hour can be extracted. Further, this feasibility study can be used as reference for implementing aforementioned energy saving strategies for the existing vapour compression chiller-based district cooling system and for analyzing similar energy saving scenarios of any type of existing system.