A Study on Waste Heat Recovery in Drain Water with Water-to-Water Heat Exchanger in Barbershops

Heat utilization efficiency of barbershop was about 16.7% in China, because the low-temperature waste water at 30～36°C was directly discharged into sewer. And match of energy grade was not appropriate, because electric water heaters were used to producing hot water at 55～70°C in most of barbershops. A waste heat recovery system with water-to-water heat exchanger (WHR-HE) was presented, according to heat utilization characteristics of barbershop and scientific principle of energy utilization. WHR-HE was analyzed by the first Law of thermodynamics and economics. The analyzed results show that energy consumption can be reduced about 75%, and incremental payback period is less one year for WHR-HE. There is optimal cold side temperature difference of water-to-water heat exchanger.