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This research aimed to simulate and optimize chilled water circuit system of a central air conditioning plant applied for a five-star hotel in Bali Island, Indonesia. This optimization was performed because temperature of chilled water distributed to the loading system could not satisfy room temperature requirement. Detailed measurements have been taken on the AC system included refrigeration system of the chillers, chilled water and cooling water distribution, cooling load, heat rejection and pumping systems. Thermodynamic analyses on the system energy performance were carried out. Numerical simulations were also established to evaluate chilled water flow rate in the primary and secondary circuits. The measurement and simulation results showed there was unbalanced chilled water flow rate between primary and secondary circuits and the chilled water flow rate did not comply with rule of flow ‘primary flow must always be equal to or greater than secondary flow’ resulted in the cooling load coils lost their cooling capability. Optimization on the chilled water flow rate between primary and secondary circuits by implementing variable speed pumping system incorporated balancing valve was estimated to be potentially improve temperature performance and economic viability of the chiller plant operation.

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Split air conditioning is the most widely used in the community for both commercial and domestic purpose. But it can cause inefficiency or waste of energy use by the system. For this reason, it is very important to keep the system working in optimum conditions to prevent wasteful use of energy by the air conditioning system. This research will re-investigate the effect of the superheat degree of refrigerant coming out of the evaporator on the system’s energy consumption. This research is conducted by analytical methods and experimental methods whose implementation includes; designing and manufacturing of experimental equipment, installation of measuring instruments experimental data retrieval, data processing and yield analysis. Data processing is done by using thermodynamic methods to get the desired quantities such as; compressor power consumption, refrigeration effects and coefficient of performance (COP). The results were carried out by quantitative descriptive method, namely by analysing changes in the superheat degree of compressor energy consumption. Based on the analysis results show that if degree of superheat is increased, compressor energy consumption increases for all refrigerants used. Whereas COP system decreases for R22 refrigerant, is relatively constant for R410a refrigerant and raises an increase for other refrigerants tested.

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