Performance prediction of a new integrated central cooling plant for energy efficiency and comfort enhancement

Abstract

The effective design of an energy efficient heating, ventilation and air conditioning system is reliant on multiple components. Among others, the air-handling unit cooling coil and its ability to perform efficiently directly influences heating, ventilation and air conditioning system performance. This paper investigates the energy and thermal performance of a water-cooled central cooling plant when combined with a direct evaporative cooling system located between the cooling tower and cooling coil of the air-handling unit. The evaporative cooler uses the water made by cooling tower to reduce the temperature of the 100% ambient air. The cooled air then passes through the cooling coil. This paper will demonstrate a series of mathematical models of the system components and validate them against experimental results. For this purpose, the central cooling plant is extensively equipped with a number of sensors and instrumentation devices for experimentation and data collection. The influence of the evaporative cooler on the energy saving potential and thermal comfort of the central cooling plant is evaluated. The advantages of this proposed hybrid system rests with the fact that the refrigeration effect of the chiller’s evaporator is decreased, which causes reduction of compressor power consumption. Results show that the hybrid system can provide average monthly energy savings between 11% and 24%, while enhancing the comfort level inside the building. Practical application: With traditional heating, ventilation and air conditioning systems contributing to 40% of a building’s overall energy consumption, the public’s increasing reliance on them as a necessity rather than a luxury is an issue in urgent need of attention. This together with a growing demand for cost-effective infrastructure and appliances has necessitated new installations and major retrofits in occupied buildings to achieve energy efficiency and environmental sustainability. The aim of this paper is to present a new integrated heating, ventilation and air conditioning system to meet these requirements without compromising comfort and indoor air quality.