Abstract

This study investigated the annual energy saving potential and system performance of two different evaporative cooling-based liquid desiccant and evaporative cooling-assisted air conditioning systems. One system used an indirect and direct evaporative cooler with a two-stage package to match the target supply air point. The other was equipped with a single-stage, packaged dew-point evaporative cooler that used a portion of the process air, which had been dehumidified in advance. Systems installed with the two evaporative coolers were compared to determine which one was more energy efficient and which one could provide better thermal comfort for building occupants in a given climate zone, using detailed simulation data. The detailed energy consumption data of these two systems were estimated using an engineering equation solver with each component model. The results showed that the liquid desiccant and dew-point evaporative-cooler-assisted 100% outdoor air system (LDEOAS) resulted in approximately 34% more annual primary energy consumption than that of the liquid desiccant and the indirect and direct evaporative-cooler-assisted 100% outdoor air system (LDIDECOAS). However, the LDEOAS could provide drier and cooler supply air, compared with the LDIDECOAS. In conclusion, LDIDECOAS has a higher energy saving potential than LDEOAS, with an acceptable level of thermal comfort.

Highlights

  • In recent years, liquid desiccant and evaporative cooling-assisted air conditioning systems, such as decoupled heating ventilation and air conditioning (HVAC) systems that are configured to be separately responsible for the latent load and sensible load of a served room, have shown energy-saving potential and has been attracting significant interest [1,2,3,4,5]

  • The thermal load was composed of three parts—the liquid desiccant (LD) side demand in the cooling season (Q_LD), reheating (Q_RHC), and parallel heating (Q_Parallel heating) during the heating season

  • The LD systems used in the LDEOAS demanded more annual thermal load than that used in the LDIDECOAS

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Summary

Introduction

Liquid desiccant and evaporative cooling-assisted air conditioning systems, such as decoupled heating ventilation and air conditioning (HVAC) systems that are configured to be separately responsible for the latent load and sensible load of a served room, have shown energy-saving potential and has been attracting significant interest [1,2,3,4,5]. The liquid desiccant and indirect and direct evaporative cooling-assisted 100% outdoor air system (LDIDECOAS) proposed by Kim et al has shown desirable energy-saving and indoor environmental quality enhancement potential, compared to the conventional variable air volume (VAV) systems [1]. The liquid desiccant (LD) system dehumidifies the SA to account for the latent load of the served room, and the evaporative cooler is responsible for the sensible load to maintain the target temperature of the served room. Existing studies show that HPs have been widely researched in terms of their high efficiency [6,7,8,9]

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