Research On Energy Saving Operation Mode Of Multi-split Air-conditioning System In Chongqing Area

The multi-split air-conditioning system, which is the so-called variable refrigerantvolume (VRV for short) air conditioning system, was invented and published byDAIKIN in1982. It is developed from the traditional room split air conditioner, and itrealizes the connection of one or more outdoor units and lots of indoor units. Comparedwith the traditional central air-conditioning system with the combination of watercooled chiller, hot water boiler and terminal equipment, it is easier and more convenientto be designed, installed, operated and maintenance managed. Besides, it saves thearchitecture space where the refrigeration room and the boiler room is installing, so alarge sum of initial investment costs will be saved and more profit will be got back inthe high house-priced and high land-priced buildings, such as office building, shoppingmalls, hotels etc.At present, the multi-split air-conditioning system is widely applied in theair-conditioning market. However, along with the great popularization and wideapplication range, there are more and more disadvantages of the traditional air cooledmulti-split air-conditioning appearing. In this background, Water cooled multi-splitair-conditioning system, as a new type of VRV system, was invented in the20th century.In fact, it is regarded as an air-conditioning system with the combination of themulti-split air-conditioning system and the water source heat pump air-conditioningsystem or the water-loop heat pump air-conditioning system. The outdoor unit of watercooled multi-split air conditioning system can be installed in different floors, so theheight difference of the ourdoor unit and the indoor untit is shorter or even eliminated,so that this system can be widely applied in the high-rise buildings and the multi-storeybuildings. In addition, the length of its refrigerant line is shorter, so the resistance loss ofrefrigerant line is smaller, and the refrigeration capacity attenuation owing to big lengthof refrigerant line becomes shorter, and the energy efficiency of the multi-splitair-conditioning system is higher. Why the initial investment of the water cooledmulti-split air-conditioning system is more than the traditional multi-splitair-conditioning system, is that it is equivalent to a set of water system based on themulti-split air-conditioner. According to the above, the promotion and application of thewater cooled multi-split air-conditioning system in Chongqing area hasn’t maken greatprogress. Through transforming a project of the air cooled multi-split air-conditioningsystem that has been put into use, a water cooled multi-split air-conditioning system canbe designed. To calculate the resistance loss of the refrigerant line is the focus of thisthesis. Through calculating the resistance loss of the typical refrigerant lines in the twosystem types, the reduction of refrigerating capacity and energy efficiency ratio (EER)of both systems can be compared and analysed. On the other hand, through calculatingthe initial investment and the running cost in a year of each system type, the economicanalysis and comparison of water cooled multi-split air-conditioning system and aircooled multi-split air-conditioning system can be maken for the use of water cooledmulti-split air-conditioning system in Chongqing area.