The Study Of Heat Storage And Emission Characteristics Of Different Heat Storage Materials-air Heat Exchanger In Sunlight Greenhouse Thermal Envirnment

At first, this paper analyzes the dynamic heat transfer process and performance of soil-air heat exchanger system, which is at the basis of analysis of data. And this paper also compares the heat transfer characteristics of soil air heat exchanger in experimental condition in between sunny day and cloudy day. Results show that soil-air heat exchanger have excellent operational state in sunny days. And the highest soil-air heat exchanger system COP can be 24.1, which represents the remarkable energy saving benefits.In the second place, three dimensional transient model is established on the basis of the experiment of soil air heat exchanger in the solar greenhouse. Gambit is used to establish the geometry and mesh. And using programming based UDF in the fluent15.0 compile the function that the temperature in heat transfer tubes changes over time. Unsteady three-dimensional numerical simulation carried out by fluent15.0 software, which is used to forecast the heat exchange process in tubes under different wind speed. Studying on air temperature variation of heat transfer tubes at different inlet velocity could help us to understand the heat transfer performance under different inlet velocity. The results show that: At the same inlet temperature of the heat transfer tubes, the heat exchanger temperature difference is bigger when the inlet velocity of air is smaller. When the wind speed reaches 5.5m/s at the experimental situation, the COP of heat exchange system is maximized, so the best velocity of the air from the air-soil heat exchanger system should be set to 5.5m/s.Furthermore, after get the optimal operational wind speed of system, the soil heat storage layer of air-heat exchanger is added four kinds of heat storage materials in this paper respectively, including the original soil, industrial regenerative wastes, Na Cl solid salt and heat storage concrete. And the heat transfer characteristics of air-heat exchanger are studied. As the filling material of heat storage layer, the research results show that the Na Cl solid salt has good heat storage performance, and its thermal stability is the best one in the four kinds of heat storage materials. The heat storage performance and thermal stability of heat storage concrete is just behind the Na Cl solid salt. Heat storage performance of industrial waste and soil is below the heat storage concrete. Although the heat storage performance of industrial waste is superior to the soil, the thermal stability of the heat storage concrete is worse than the soil. So in sunlight greenhouse, according to these four heat storage materials at the periodical thermal and humidity environment, the best heat storage material of soil-air heat exchanger shall be the Na Cl solid salt.