Abstract
Condenser evaporative pre-coolers provide a low cost retrofit option for existing packaged rooftop air conditioning application units. This paper aimed to provide a comprehensive study to assess energy savings and peak power reductions of condenser evaporative cooling. Condenser evaporative cooling leads to a lower temperature of the air entering the condenser of a rooftop unit, which results in smaller compressor power consumption. Using EnergyPlus building energy simulations, we mapped the impacts on energy savings and energy reductions at peak ambient temperatures in three building types and 16 locations with levels of pad effectiveness and demonstrated the effects on air conditioner using either R22 or R410A as refrigerants. Economics and control strategy to maximize the cost saving were also investigated. The results demonstrate that energy savings are much greater for HVAC systems with the refrigerant R410A than they are with R22, and evaporative pre-cooling provides the opportunity for annual energy savings and peak demand reductions, with significant potential in hot, dry climates. Additionally, we validated an improved mathematical model for estimating the condenser pre-cooling wet bulb efficiency which shows clear advantage over the current EnergyPlus model.
Highlights
Evaporative cooling is a process that cools air through the simple evaporation of water
When applied to outdoor air, the wetted media cools down the air entering the condenser coil and the process is called evaporative pre-cooling
We introduced a mathematical model to correlate the wet bulb efficiency of an evaporative-precooling pad, which requires less data points for fitting and has better accuracy than the current model used in EnergyPlus [11]
Summary
Evaporative cooling is a process that cools air through the simple evaporation of water. It should be noted that the seven locations include a very humid climate zone like Panama City, where the evaporative pre-cooling saving is less significant At the end, they concluded the payback periods to cover the retrofit cost (pad, pipe, pump, etc.) are less than 2 years. Eidan et al, [10] studied the effects of condenser evaporative pre-cooling on a small window air conditioner in Iraq’s climate where the air temperature can reach 55 ◦ C They reported that the precooling was able to extend the working range to the extreme temperature, and reduce peak power consumption. This work intends to provide a comprehensive reference evaluation, in terms of annual energy savings, peak power reduction, water consumption, payback period, for applying the condenser evaporative pre-cooling technique nationwide. Energy and economics saving potentials were revealed with respect to the multiple influential factors
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