This paper is made up of four main parts:the background of heat circuit,a brief introduction of heat circuit,the method to select suitable working fluids and a set of heat circuit working fluids,the method to determine the charge of working fluids.

Research on cycle working fluids for moderate and high temperature heat pump systems;

Inquiry on matter circulation and energy circulation in a food chain in Heidong Cave of Guizhou Province;

The traditional core theory of ecology is “matter circulation” and “ecology b alance”,which cultivates the concept that the limited physical resources can be exploited limitlessly through matter circulation,setting the foundation for the theory of constant stability of ecology.

the essay analyzes characteristics of matter circulation of agricultural eco-economysystem in high cold and semi-arid area of Bashang by taking yejia village for an instance.

Review of studies on the classification,application and material cycle of plants in genus Carex;

In this paper, after accumulating the older generations experience and sorting out a wealth of material, the author analized the basic principles of material cycle in ecological system of forest, and investigated the nutrient utilizing in forestry management.

Research on the energy conversion and material cycle in agro-ecosystem was carried out in zhangbei experimental area in the years of 1986￣1988.