Energy conservation potential of an indirect and direct evaporative cooling assisted 100% outdoor air system

This study aims to present the fundamentals in which operation of a 100% outdoor air system integrates with indirect and direct evaporative cooling systems and to estimate its energy saving potential. The simulation of the proposed system is performed using a commercial equation solver program, and the annual operation energy saving potential with respect to a conventional variable air volume system is determined. This paper shows that significant operation energy savings (i.e. 21–51% less energy consumption) is possible principally by the pre-conditioning of supply air due to the waste heat recovery using the indirect evaporative cooler and the sensible heat exchanger units. By components, the proposed system shows a 16–25% less annual cooling coil load and an 80–87% reduced annual heating coil load with respect to the conventional variable air volume system, while there is no fan energy savings expected. Practical applications: This paper provides practical insight on how the evaporative cooling based 100% outdoor air system operates and how each essential component, such as the indirect evaporative cooler, cooling coil, direct evaporative cooler, heating coil and sensible heat exchanger should be controlled during the seasons for realising energy conservation benefits. The sequence of operation presented in this paper can be implemented to actual control logic.

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Energy-saving potential of dedicated outdoor-air system assisted by vacuum-based membrane dehumidifier

E3S Web of Conferences ◽

10.1051/e3sconf/201911101087 ◽

2019 ◽

Vol 111 ◽

pp. 01087 ◽

Cited By ~ 1

Author(s):

Seong-Yong Cheon ◽

Soo-Yeol Yoon ◽

Su Liu ◽

Jae-Weon Jeong

Keyword(s):

Energy Saving ◽

Primary Objective ◽

Dew Point ◽

Outdoor Air ◽

Variable Air Volume ◽

Energy Saving Potential ◽

Air Volume ◽

Air Supply ◽

Radiant Cooling ◽

Air System

The proposed research presents a dedicated outdoor-air system (DOAS) integrated with a vacuumbased membrane dehumidifier (VMD). The primary objective of this study was to evaluate the energy-saving potential of the proposed VMD–DOAS combination. VMD–DOAS comprised a membrane-energy exchanger (MEE), dew-point indirect evaporative cooler (DP-IEC), and VMD. VMD possessed a characteristic by virtue of which the dehumidification process was isothermal; i.e., no temperature change was observed during the VMD process. While VMD served to control the dry-air supply, the required target temperature (i.e., 17 °C) was maintained via DP-IEC operation. The remaining sensible heat of the conditioned zone was controlled by the ceiling radiant cooling panel (CRCP). The load of the conditioned zone was driven by TRANSYS 18, and an engineering equation solver (EES) was used for evaluating the energy-saving potential of the proposed system with CRCP by comparing it against the variable-air-volume (VAV) system. Results of this study demonstrated that the proposed DOAS with CRCP consumed 37% less operating energy compared to the VAV system. This observed energy-saving potential of the proposed system was driven by reducing the dehumidification load and subsequent energy recovery by MEE.

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Sterilization effectiveness of in-duct ultraviolet germicidal irradiation system in liquid desiccant and indirect/direct evaporative cooling-assisted 100% outdoor air system

Building and Environment ◽

10.1016/j.buildenv.2020.107350 ◽

2020 ◽

Vol 186 ◽

pp. 107350

Author(s):

Jong-Il Bang ◽

Joon-Young Park ◽

Ye-Lim Jo ◽

Jae-Weon Jeong ◽

Anseop Choi ◽

...

Keyword(s):

Evaporative Cooling ◽

Outdoor Air ◽

Liquid Desiccant ◽

Ultraviolet Germicidal Irradiation ◽

Irradiation System ◽

Direct Evaporative Cooling ◽

Air System

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Energy Performance Comparison between Two Liquid Desiccant and Evaporative Cooling-Assisted Air Conditioning Systems

Energies ◽

10.3390/en13030522 ◽

2020 ◽

Vol 13 (3) ◽

pp. 522

Author(s):

Su Liu ◽

Jae-Weon Jeong

Keyword(s):

Energy Consumption ◽

Air Conditioning ◽

Evaporative Cooling ◽

Dew Point ◽

Outdoor Air ◽

Liquid Desiccant ◽

Energy Saving Potential ◽

Evaporative Cooler ◽

Air Conditioning Systems ◽

Direct Evaporative Cooler

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.

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