Performance enhancement of existing air conditioning systems

The performance of an existing 5 ton (17.7 kW) air conditioning system with an EER of 8 has been simulated by retrofitting it with a two-phase natural circulation heat recovery loop and an evaporatively cooled condenser. The author has developed a simulation program for predicting the performance of existing air conditioning systems with one or both of the above retrofits for the performance enhancement. The performance of the air conditioning system is simulated for hot and humid climates which are typical of the south eastern United States. The performance data along with an economic analysis has been presented in the paper. This investigation shows that by retrofitting an existing 5 ton air conditioning system with a two-phase natural circulation heat recovery loop and an evaporatively cooled condenser, the operational cost and the peak demand are reduced. Hence, there is a cost impact from both the utility and the consumer perspective. This also results in an increased dehumidification which improves the indoor air quality; and reduces compressor power. The results show that the system performance increases by 84.4% and results in a diversified peak reduction of 6.78 kW. For the present investigation, a combination of the above two retrofits will pay for itself in 0.71 year. On the basis of this investigation it is recommended that two-phase natural circulation heat recovery loops and evaporatively cooled condensers may be used for a demand side management (DSM) program for reducing energy consumption and peak demand for air conditioning in the residential and commercial sectors