Question

Cooling tower is a special recycling device which applies the heat rejection process. Figure Q4 (a) shows the cooling tower system that extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Sketch the water recycle in the cooling tower Q4 (a) (5 marks) High leaving water temperature will cause a drop in process cooling efficiency, increasing system power consumption, creating physical discomfort to people within an air-conditioned area, and have a detrimental effect on other system components. In order to achieve optimum efficiency for operation and maintenance, discuss the major factors that affecting cooling tower performance in leaving water (b) temperature. (8 marks) d Compressed air is used in most manufacturing and some service industries, often where it is impractical or hazardous to use electrical energy directly to supply power to tools and equipment. Figure Q4 (d) show the airpower tool and electric power tool used today. List the differences between these two types of power tools. (7 marks) The refrigeration cycle begins with the refrigerant in the evaporator. When leaving the evaporator, the refrigerant has absorbed a quantity of heat from the product and is a low-pressure, low-temperature vapour. Discuss suitable methods in maintaining the refrigerant operation for optimum (e) energy efficiency (5 marks)

Answer 1