Abstract
This study experimentally investigates the performance of a helical coil integrated chilled water system (HCCWS) used for simultaneous cooling of hot air (HA) and water (HW). The current HCCWS operates with three fluids in which chilled water (CW) flows inside the shell while hot water and air pass through the helical coil and innermost tube. Nusselt number, friction factor, and JF factor are measured as performance of the HCCWS corresponding to variations in inlet temperature, flow rate, and velocity of different fluids respectively. Temperature distribution of different fluids along the length of the HCCWS test section was determined. From results, it is observed that Nusselt number increases considerably as the flow rate of CW increases, reaching a maximum of 150.01 at a flow rate of 200 liter per hour (LPH) and an inlet temperature of 13°C. As the flow rate of chilled water increases, the friction factor drops. The lowest friction factor measured was 0.016 with a flow rate of 200 LPH and an inlet temperature of 13°C. The chilled water inlet temperature and hot water flow rate significantly affect the JF factor of CW, HW, and HA with a contribution of 33.47%, 33.7%, and 32.69%, respectively. The Taguchi-Grey technique was used to optimize the overall JF factor corresponding to input parameters. The optimal HCCWS performance was achieved at 13°C inlet temperature, 100 LPH chilled and hot water flow rates, and 4 m/s hot air velocity, raising the grey relation grade to 1.
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