Life Cycle Management of a Low-Rise Building with a Heat Pump System under Conditions of Overheating in a Compression Circuit
Abstract
Introduction . While a heat pump system is operating, the entry of vapor-liquid refrigerant droplets into the high-pressure zone is not acceptable, as it results in cavitation and equipment failure. Effective control of vapor superheat at the evap-orator outlet is key to ensuring safe and energy-efficient system operation. The aim of the study is to develop an algorithm and software for evaluating the evaporation kinetics of refrigerant droplets in the suction line in order to prevent cavitation and boost the energy efficiency of a system. Materials and Methods . The study is based on a numerical algorithm for the problem of vapor-liquid refrigerant droplet evaporation kinetics. The algorithm includes automatic interpolation of the thermal and physical properties of liquid and gaseous freons at the evaporation line, calculation of kinematic viscosity, similarity criteria (Archimedes, Reynolds for evaporation), and identification of the average evaporation rate in a specific temperature gradient from –10 to +15 °C in 5°C increments at a pressure of 5 bar. Research Results . A software application has been developed for modeling droplet evaporation parameters depending on the rheological properties of freons (R134a, R407C, R410A, R32). Calculations of the average vapor velocity were made at the evaporation line for droplets with diameters from 0.1 to 1.0 mm in the temperature ranging from –10 to +15 °C. Tabular and graphical dependences of the evaporation rate on the diameter of evaporating droplets for various refrigerant grades were obtained. Discussion and Conclusion . The results enable us to evaluate the impact of heat and mass transfer on the energy efficiency of the freon circuit recirculation and to optimize the steam superheating parameters. The program can be employed as a digital twin for lifecycle management of a construction project with a heat pump system, as well as for developing some practical recommendations for identifying the ratio of the residence time of droplets in the steam flow and their evaporation time.