The design, good or bad, of heat exchangers has a big influence on the performance of an air-conditioner. It became a prime task to develop a heat exchange simulator which could cut back on the number of experimental production units and to improve the quality of design, in order to develop and produce highly efficient green heat exchangers at a moderate price.The experimental production costs are high and duration of tests can be long, particularly when developing heat exchangers for middle or large size air-conditioners of limited numerical quantity. The simulators using conventional "Procedure Oriented Programming^(*5)" are difficult to correspond quickly to data change of constituents such as shape, size of cupper pipe, aluminum fin and various refrigerants etc., so there was no appropriate simulator for heat exchanger in this field.

Fujitsu General Ltd. made an agreement with Shanghai Jiaotong University on April 2002 to solve the problems. Together, they started to develop a simulator for the heat exchanger of air-conditioners.

The collaboration of the background of outstanding development and production power of FGL and excellent simulation technologies of Shanghai Jiaotong University, succeeded in developing a world first^(*1) simulator for heat exchangers applying the "Object Oriented^(*2) Programming^(*3)", which is scarcely influenced by data change of constituents.

1. Results of collaboration:
   1. It is important to group the functions such as structure of heat exchanger, operating conditions, the properties of refrigerant and air, and so forth into independent ones (object), so as to apply "OOP" to optimize a heat exchanger design by changing data of the constituents. We are able to simulate a heat exchanger efficiently without any influence of data changes of constituents, bringing the characteristics of "OOP" into play by grouping objects consisting of "components" such as copper pipe and aluminum fin etc., "evaporation function" and "condensation function" in our new heat exchanger simulator. When to change the data of constituents we have succeeded to use the simulator without any modification of the simulator but only by adding and/or changing data in the corresponding groups (class) according to the new design.
   2. he software of "REFPROP", which becomes a global standard of thermodynamic and transport properties of refrigerants and refrigerant mixtures data base, is used to simulate a heat exchanger. But the "REFPROP" is written by "FORTRAN" (Procedure Oriented Language^(*5)), so it is impossible to call "REFPROP" directly under C++ (Language for OOP). To solve the problem we have developed a new means of data transmission named "Data calling between different languages", which can call the "REFPROP" written by FORTRAN under "C++". By the new method we can call the properties of refrigerants in "REFPROP" easily and efficiently, and have achieved to apply "OOP" to our heat exchanger simulator.
2. The features of our heat exchanger simulator
   The heat exchanger simulator applied "OOP" can,
   
   1. Correspond to data change of constituents of heat exchanger easily and make productivity better.
   2. Do maintenance easily since the influence of data change of constituents is small.
   3. Make the simulator upgrade easily.
   Because of above reasons development period of heat exchangers is expected to cut down and this technology has expansibility that "OOP" may be applied to a simulator for refrigeration cycle. (Up to now it has taken several hours to few days, but the simulator can measure the same performances of it in few minutes.)

2 patents are under application at the moment.

1. To develop more accurate heat exchanger simulator using "OOP".
2. We will develop new efficient air-conditioners for Chinesemarket by using the simulator collaborated with Shanghai Jiaotong University.