A new installation called the open-type heat-source tower was introduced and its structural features and principle of operation were analyzed in this paper.Its applicability,status quo and prospects of application in heating,ventilation and air-conditioning(HVAC)systems were discussed.It was concluded from the analysis that the open-type heat-source tower can be used as the heat source of the air-conditioning system in winter and as the cold source in summer.With this dual-purpose installation,the purposes of comprehensive utilization of resources and reducing of energy consumption can be attained.This new technology will be applicable especially in the south of China.It could effectively solve the problem of frost formation in the air-source heat pump running in winter and substitute for the ground-source heat pump which are used limitedly in those regions.

Compares three typical heat-source towers with different structures, namely open structure, common closed structure and improved closed structure in aspects of working principle, application characteristics and performance, etc. It is found that each type has its own merits and shortcomings separately. For the open type, it has simple structure, smaller investment, higher thermal efficiency, while the working fluids (cooling water in summer or antifreeze in winter) lose greatly in the process, besides the freezing temperature of antifreeze is unstable due to absorption of moisture in air during winter. For the common closed type, there is no worry of frosting problem in winter, also drifts of the working fluids are reduced greatly, which are attributed to the adoption of coil-heat exchanger with broader fins, yet the thermal efficiency is lower. For the improved closed type, it combines the merits of above two types, showing better performance in the operation, being worth to be popularized and investigated extensively.

The structural and operational characteristics between two kinds of pulsating heat pipes(PHPs) were compared.It is revealed that the flat plate type PHPs with square channels has two structural characteristics distinct different from the circle tube type PHPs,such as the sharp angled edges and the transverse heat balance effects through the thin wall between two neighboring channels,which contributed to the distinct operational characteristics.Experiments show that in the horizontal and vertical top heat modes,both type PHPs have the same optimum filling ratio ranging from 40% to 70%;in the vertical bottom heat mode,the circle tube type PHPs has an optimum filling ratio ranging from 30% to 70%,while the flat plate type PHPs with square channels has an optimum filling ratio of about 15%.

A new device called closed-type heat-source tower was discussed in aspects of structural characteristics,working mechanism,and current applications in HVAC(Heating,Ventilation Air Conditioning) system.It is found that this new device can supply cold and heat energy source for the HVAC system in summer and winter respectively,showing potential prospects,such as higher efficiency,space and investments saving,etc.Due to the short-time in practice,this new device still needs to be improved or optimized in respect to its structure and operating parameters,also the heat and mass transfer process needs to be investigated in theory and experiments.