The Effects of Capacity Coupling and Wet Air Return on the Energy Performance of Chiller-Cooling Tower Systems

2011 ◽  
Vol 27 (4) ◽  
pp. N25-N31
Author(s):  
C.-W. Liu ◽  
Y.-K. Chuah
Keyword(s):  
Relative Efficiency ◽  
Cooling Tower ◽  
Load Ratio ◽  
Regression Function ◽  
Energy Performance ◽  
Coupling Ratio ◽  
Performance System ◽  
System Energy ◽  
Novel Concept ◽  
Tower System

ABSTRACTThis study uses a novel concept of capacity coupling of chiller-cooling tower system to investigate the system energy performance. System performance factor (SPF) of the chiller-cooling tower system is used in the analysis. A regression function is obtained for hourly reset of condensing water temperature so to achieve maximum SPF. The regression function includes parameters such as ambient wet bulb temperature, chiller load ratio, tower capacity ratio, and a dimensionless relative efficiency of chiller and cooling tower. The regression function has an R2 close to 1 compared to the computed results. It is found that for capacity coupling ratio of 1.1 ∼ 1.6, SPF would increase by about 3 ∼ 6% compared with a typical base control. The effect of wet air return is presented as an equivalent wet bulb temperature. It has been found that SPF would decrease significantly when higher equivalent wet bulb temperature occurs at the tower inlet.

Field Testing of Water Source Heat Pump Systems in Chongqing of China

2012 ◽  
Vol 516-517 ◽  
pp. 302-307
Author(s):  
Xue Lian Bai ◽  
Ning Yi Liu ◽  
Ke Hui Cheng ◽  
Yi Cheng Liu
Keyword(s):  
Energy Efficiency ◽  
Heat Pump ◽  
Energy Resource ◽  
Load Ratio ◽  
Water Source ◽  
Energy Performance ◽  
Operating Conditions ◽  
Water Transportation ◽  
Partial Load ◽  
System Energy

As an application technology of renewable energy resource, water source heat pump (WSHP) has been paid more attention on. WSHP have been practiced especially for saving building energy consumption in Chongqing of China since there is abound water resources. However, it was found that some systems were not operated very well without achieving expected energy efficiency. Taking three real projects which use WSHP for heating and cooling of buildings in Chongqing city to test in field, key parameters were measured and operation performances were analyzed. The influences of water temperature and partial load ratio on system energy efficiency were studied. Based on existing problems, strategies for improving system energy performance are suggested from aspects of design and operating. Dynamic load hourly simulation plays a key role to determine appropriately the size and the form of system. More efforts have to be put on water pumps arrangement to save energy consumed for water transportation which accounts for large part of system energy. The temperature difference and water quality of water source should be controlled according actual operating conditions. The integrated systems and operation strategies under partial load are also beneficial for efficiency improvement.

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