The air cooled packaged chiller is a very popular choice for HVAC designers in capacities up to and slightly above 1,900 kW (550 tons). Until recently, the only compressor types commonly available in air cooled packaged chillers across that entire range were of the positive displacement type. By contrast, for nearly 100 years, the efficiency and other inherent advantages of centrifugal compressors have made them a popular compressor choice in water cooled packaged chillers with capacities as low as 350 kW (100 tons). This article explores the history of centrifugal compressors when applied in air cooled chiller systems.

Although counter intuitive, using a heat pipe air-to-air heat exchanger in summer for both sensible cooling (Indirect) and adiabatic cooling and humidification (Direct) of the outdoor air in an arid climate can reduce peak refrigeration tonnage while exceeding Standard 62.1 outdoor air ventilation for a Natatorium. Heat recovery in cold ambient conditions allows the system to exceed minimum code outdoor air flow requirements into the Natatorium to dilute and remove Chloramines and maintain a better Indoor Air Quality ( IAQ) in the pool enclosure without additional heating costs. This case study analyzes the Aquatic Center project installed in Dublin, California.

This conference paper explores the ever-changing dynamic of air-cooled versus water-cooled systems. While water-cooled systems still often reduce the building energy use, there have been dramatic improvements in air-cooled chiller performance. There is increasing concern with fresh water scarcity as we acknowledge the cost and energy consumption required at desalination and water treatment plants. And there’s major growth of renewable power generation in the grid energy mix which affects both the process water use and greenhouse gas emissions. The market’s demand for sustainability, energy efficiency, and water efficiency must be weighed carefully as competing interests continue to evolve over the next decade.

Roof top equipment is often concealed for aesthetics reasons, by a solid or louvered parapet walls aka “Architectural Screens”. This results in inefficient dispersion of exhaust air and reduces the thermal efficiency of the equipment inside the screens. This work estimates excess energy used at an 8000 tons district cooling plants when cooling tower fan operates at higher speeds to compensate for the entrainment and recirculation of exhaust air caused by architectural walls around a cooling tower. Air properties for two locations: 1) inside the walls near the cooling tower and 2) away from it, outside the walls were monitored and analyzed.

There are nearly 60 thousand Mosques spread across the Kingdom of Saudi Arabia, consuming nearly 3 Terawatt-Hour of site electrical energy, 70% of which is due to the use of mostly inefficient HVAC systems. It is estimated that 20 million M³ of expensively treated water used annually for ablution, 50% of which flows directly to the drain without any contamination. This paper evaluates the potential savings in water and energy of reusing ablution water to run mosque Air-Conditioning systems using high efficiency IDEC technology.