AIR CONDITIONING
Traditionally, air conditioning systems regulate refrigerant operating temperatures within a very small variable.
The range of temperatures are important to optimise heat exchange, satisfying the requirements of the room load. Generally, these are set and produce the rated capacity of the system when operating at 100% load in particular conditions; evaporating temperature being the main focus when providing cooling. The difference between evaporating temperature and condensing temperature is key to establishing a good system efficiency.
Variable Refrigerant Flow systems offer multiple indoor fan coils serving individual areas, each responsible for its own individual load. As fan coils are turned off, the load placed on the system reduces. This load reduction is generally managed by adjusting the compressor rotation speed and in turn the amount of refrigerant flowing around the system. Whilst the system will consume less power, the ratio of power consumed to capacity produced remains in part on a linear line.
By using technologies like Intelligent Refrigerant Control, the evaporating temperature of the refrigerant can be adjusted in relation to
the buildings load. This can be monitored and reacted upon in relation to fan coil performance and also to outside ambient temperature. The higher the evaporating temperature, the smaller the difference is to the condensing temperature and therefore the efficiency of the system improves. The overall efficiency is still related to the ambient temperature in terms of seasonal variations, but it is much more fluid and sees seasonal efficiency ratios increase up to 24%. Comfort levels are also increased because of a more stable operation with less thermostat on/ off cycling.
Tighter policies enforcing the application of technologies usually overlooked; contained within air conditioning products will drive down
energy consumption. Identified as the critical improvement in an air conditioning systems operation, control, in the broad spectrum should not be left to chance. We should utilise the concept of AI where possible in both room temperature control and integrated control strategies.
Seasonal efficiency gains of 24% is a substantial gain and the application of Intelligent Refrigerant Control on a global level will assist in working towards the IEA’s alternative efficient cooling scenario. This models with products with SEER ratings of up to 80% higher by 2050 contributing to reduced operating costs, reduced demand on the national grid and a reduction in CO2
emissions.
www.acr-news.com
September 2020 23
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