CO2 heat pump for waste heat recovery and utilization in dairy industry with ammonia based refrigeration

Based on field data from a medium scale ammonia based milk refrigeration plant located in northern India, a trans-critical CO2 heat pump system with IHX is conceptualized for waste heat utilization. The waste heat is utilized to pre-heating the boiler feed water and thereby reduces energy consumption. A thermodynamic model of the refrigeration system is built and simulated for year-round field data. In this study, the condenser of the ammonia based refrigeration system is coupled with the evaporator of the proposed CO2 heat pump which is maintained at 20 degrees C year-round. The heat pump delivers heat at about 70 degrees C to pre-heat the boiler feed water drawn from underground source and is available in temperature range of 25 degrees C to 29 degrees C year-round. Thus, the CO2 heat pump performance is essentially independent of variation in ambient temperature. We reported reduction in CO2 emission and reduction in total energy cost by approximately 45.7% and 33.8% respectively. Economic analysis shows the payback period (PBP) is about 40 months. (C) 2017 Elsevier Ltd and IIR. All rights reserved.