| With the development of multi-connected unit air conditioning systems, the applications of multi-connected unit air conditioning systems in small-medium office/commercial-residential building are increased. While this system is able to change cooling or heating capacity to match building load which change hourly, the energy saving potential of multi-connected unit air conditioning systems in project is affected by multiple factors.This paper aims to study the factors that affectenergy efficiency of digital scroll multi-connected unit air conditioning systems and conventional air conditioning systems, comparative analyze the actual energy consumption of air conditionings in Chongqing. Taking two buildings which respectively apply digital scroll multi-connected unit air conditioning systems and conventional air conditioning systems for research, this papersimulate annual dynamic energy by DEST.Combined with the existing conventional air conditioning annual energy consumption model to calculate the annual energy consumption of conventional air conditioning systems, it shows that SEER of cooling season is2.65and SEER of heating season is1.04for conventional and SEER of cooling season is3.37and SEER of heating season is2.89for digital scroll multi-connected unit air conditioning systems.The formula is used to evaluate energy savings, which turn out to be0.475for cooling season and1.78for heating season.Start from the factors which affect EER of out units of digital scroll multi-connected unit air conditioning systems, this paper analyze the impact of outdoor temperature and the load rate of the outdoor unit with the manufacturers data. Then make reasonable simplification to analyze the impact of pressure drop along the pipeline and gravity,propose the definition of correction factor itobtains theoretical calculation model to calculate the EER of outdoor units. The theoretical calculation model is verified by measurement data.Based on the calculation model, this paper calculate the constitutes of energy consumption of digital scroll multi-connected unit air conditioning systems, it shows the energy proportion of outdoor units/indoor units are90%and10%in cooling season,the energy proportion of outdoor units/indoor units/outdoor unit defrost are77.4%,8.6%,14%in heating season.The method to analyze the impact of load rate and pressure drop along the pipelineand gravity on energy of digital scroll multi-connected unit air conditioning systems aresimilar to the method to analyze the impact on EER of outdoor units. It finds that loadrate interval can be descending sorted by（1.1，1.2）,（0.8，1.1）,（0.5，0.6）,（0.6，0.8）,（0，0.5）in cooling season and（0.5，0.6）,（0，0.5）,（0.6，0.8）,（0.8，1.1）,（1.1，1.2）in heating season.Based on different layouts of digital scroll multi-connected unit air conditioningsystems, this paper define the longest horizontal distance from indoor units to outdoorunits as “the longest length of refrigerant pipe”, then analyzes the impact of buildingsize and layouts of outdoor units on the energy saving efficiency. The main outcomecompletions are as follows.①SEER of digital scroll multi-connected unit air conditioning systems is affectedby the length of refrigerant pipe and height between indoor and outdoor unit. In general,as the length of refrigerant pipe, SEER is decreased.②Take buildings which the height between indoor units and outdoors units is40mfor examples, layouts of digital scroll multi-connected unit air conditioning systems aredivided to three conditions. Without considering the capacity of the electronicexpansion valve prerequisite, in the first case, which outdoor units are placed high thanthe indoor units, when the longest length of refrigerant pipe reach103m, digital scrollmulti-connected unit air conditioning systems is no longer having advantages in energysaving efficiency than conventional air-conditioning system in cooling season; in thesecond case, which outdoor units are placed at the middle of building, when the longestlength of refrigerant pipe reach75m, digital scroll multi-connected unit air conditioningsystems is no longer having advantages in energy saving efficiency than conventionalair-conditioning system in cooling season; in the third case, which outdoor units areplaced lower than the indoor units, when the longest length of refrigerant pipe reach40m, digital scroll multi-connected unit air conditioning systems is no longer havingadvantages in energy saving efficiency than conventional air-conditioning system incooling season... |
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