Characteristics Of Temperatures And Condensate For Air Source Heat Pump Water Heater

With the economy sustained and stable developing,people’s lifestyles becom more diversified and have more rational thinking to the choice of energy-intensive products in daily life. The heat pump water heater is cognitived gradually by the market because of its green, environmentally friendly, and energy-saving features.In this paper, characteristics of water temperatures for ASHP water heater is analysised by theory and experiment. And the flow heat transfer mechanism of the evaporator is in-depth exploraed. The main works are as follows:An analytical solution model is proposed for the unsteady heat conduction of a double heat exchanger. Take a directly-heated ASHP water heater as case, the unsteady temperature field experiment is conducted to measure the heat storage tank under different ambient temperature conditions. The maximum relative error of simulated and experimental results does not exceed 7%, the analytical solution model can solve the heat transfer problem. To promote analytical solution of the model, the impact to the tank water temperature distribution on structural dimensions of spiral coil and water tank is studied. The analysis showed that the horizontal structure size cause a larger influence on water temperature characteristics. Under the experimental conditions(water tank capacity of 300L), reasonable spiral radius of built-in heat exchanger coil is 0.17 m.Under different ambient temperature and air relative humidity conditions,condensate is study by the experiment. Compare Four experimental conditions, the results show that: the mean condensate amount increases 12%, when the relative humidity varies from 59% to 62% during the system operation; and the mean condensate amount decares 26%, when the ambient temperature varies from 31℃ to 35℃. Compare 15 sets experimental data(ambient temperature of 31-35℃, relative humidity of 48-78%), the study found that the condensate amount distribution with relative humidity appeares opposite variation when the ambient temperature is around 26℃. When the relative humidity is constant, and the ambient temperature is higher than 26℃, the condensate amount decreases gradually with the ambient temperature increasing.For evaporation, steady distributed parameter model is established, and zoning weighted correlation of the integrated heat transfer coefficient is proposed. At an ambient temperature of 23.8 ℃ conditions, the experimental verified the accuracy of the calculation model of comprehensive heat transfer coefficient. The error of calculated and simulated values is between 10.45% and 20.08%, which is in line with the requirements of engineering applications. The correlations can be applied to predict the heat transfer coefficien.The subject provides a theoretical basis for the study of condenser and evaporator heat transfer mechanism and the design and optimization of condenser coil structural parameters in an ASHP water system. Tt has important significance for the development and promotion of energy-efficient products.