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Title: Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions

Abstract

Air conditioner cooling coils typically provide both sensible cooling and moisture removal. Data from a limited number of field studies (Khattar et al. 1985; Henderson and Rengarajan 1996; Henderson 1998) have demonstrated that the moisture removal capacity of a cooling coil degrades at part-load conditions--especially when the supply fan operates continuously while the cooling coil cycles on and off. Degradation occurs because moisture that condenses on the coil surfaces during the cooling cycle evaporates back into air stream when the coil is off. This degradation affects the ability of cooling equipment to maintain proper indoor humidity levels and may negatively impact indoor air quality. This report summarizes the results of a comprehensive project to better understand and quantify the moisture removal (dehumidification) performance of cooling coils at part-load conditions. A review of the open literature was initially conducted to learn from previous research on this topic. Detailed performance measurements were then collected for eight cooling coils in a controlled laboratory setting to understand the impact of coil geometry and operating conditions on transient moisture condensation and evaporation by the coils. Measurements of cooling coil dehumidification performance and space humidity levels were also collected at seven field test sites. Finally, anmore » existing engineering model to predict dehumidification performance degradation for single-stage cooling equipment at part-load conditions (Henderson and Rengarajan 1996) was enhanced to include a broader range of fan control strategies and an improved theoretical basis for modeling off-cycle moisture evaporation from cooling coils. The improved model was validated with the laboratory measurements, and this report provides guidance for users regarding proper model inputs. The model is suitable for use in computerized calculation procedures such as hourly or sub-hourly building energy simulation programs (e.g., DOE's EnergyPlus building energy simulation program, http://www.energyplus.gov ).« less

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Central Florida, Orlando, FL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
881342
DOE Contract Number:  
FC26-01NT41253
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; AIR CONDITIONERS; AIR CONDITIONING; AIR QUALITY; BLOWERS; CAPACITY; EVAPORATION; FIELD TESTS; GEOMETRY; HUMIDITY; INDOORS; MOISTURE; PERFORMANCE; REMOVAL; TRANSIENTS

Citation Formats

Don B. Shirey III, Hugh I. Henderson Jr, and Richard A. Raustad. Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions. United States: N. p., 2006. Web. doi:10.2172/881342.
Don B. Shirey III, Hugh I. Henderson Jr, & Richard A. Raustad. Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions. United States. doi:10.2172/881342.
Don B. Shirey III, Hugh I. Henderson Jr, and Richard A. Raustad. Sun . "Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions". United States. doi:10.2172/881342. https://www.osti.gov/servlets/purl/881342.
@article{osti_881342,
title = {Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions},
author = {Don B. Shirey III and Hugh I. Henderson Jr and Richard A. Raustad},
abstractNote = {Air conditioner cooling coils typically provide both sensible cooling and moisture removal. Data from a limited number of field studies (Khattar et al. 1985; Henderson and Rengarajan 1996; Henderson 1998) have demonstrated that the moisture removal capacity of a cooling coil degrades at part-load conditions--especially when the supply fan operates continuously while the cooling coil cycles on and off. Degradation occurs because moisture that condenses on the coil surfaces during the cooling cycle evaporates back into air stream when the coil is off. This degradation affects the ability of cooling equipment to maintain proper indoor humidity levels and may negatively impact indoor air quality. This report summarizes the results of a comprehensive project to better understand and quantify the moisture removal (dehumidification) performance of cooling coils at part-load conditions. A review of the open literature was initially conducted to learn from previous research on this topic. Detailed performance measurements were then collected for eight cooling coils in a controlled laboratory setting to understand the impact of coil geometry and operating conditions on transient moisture condensation and evaporation by the coils. Measurements of cooling coil dehumidification performance and space humidity levels were also collected at seven field test sites. Finally, an existing engineering model to predict dehumidification performance degradation for single-stage cooling equipment at part-load conditions (Henderson and Rengarajan 1996) was enhanced to include a broader range of fan control strategies and an improved theoretical basis for modeling off-cycle moisture evaporation from cooling coils. The improved model was validated with the laboratory measurements, and this report provides guidance for users regarding proper model inputs. The model is suitable for use in computerized calculation procedures such as hourly or sub-hourly building energy simulation programs (e.g., DOE's EnergyPlus building energy simulation program, http://www.energyplus.gov ).},
doi = {10.2172/881342},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

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