HVAC dehumidification systems for thermal comfort: a critical review

Abstract This paper, on the basis of the main literature indications, deals with moisture control in buildings during the summer season; so, the dehumidification of the air is analysed. Dehumidification is considered as a key feature of HVAC systems for thermal comfort. Initially, the principles of mechanical and chemical dehumidification are shown. The first one utilises mechanical means—compression refrigeration systems—to cool the air and so to dehumidify it; the latter removes the water vapour from the air by transferring it towards a desiccant material (adsorption or absorption). In the mechanical dehumidification field, a proper control of ambient temperature and humidity can be obtained by means of an air handling unit (AHU) which treats outside air alone, while recirculating air is treated by a simple cooling coil. Various possible AHU configurations are examined. Afterwards, HVAC systems for a theatre and for a supermarket are analysed. The use of hybrid systems with desiccant wheel for these applications has provided the following main results: remarkable savings in operating costs and higher plant costs (a simple payback time of 2–3 years for supermarket); a notable reduction of the power electric demand; a better control of ambient humidity.

[1]  W. J. Coad.  Conditioning ventilation air for improved performance and air quality , 1999 .

[2]  M. J. Brandemuehl,et al.  Separating the V in HVAC: A dual-path approach , 2002 .

[3]  Andrea Gasparella,et al.  New ideas for energy utilisation in combined heat and power with cooling: II. Applications , 1997 .

[4]  B. M. Cohen,et al.  Application of gas-fired desiccant cooling systems , 1989 .

[5]  D. Calton.  Distributed air conditioning in supermarkets , 1992 .

[6]  Michael J. Witte,et al.  Evaluating active desiccant systems for ventilating commercial buildings , 1999 .

[7]  Andrea Gasparella,et al.  New ideas for energy utilisation in combined heat and power with cooling: I. Principles , 1997 .

[8]  M. Meckler.  Integrated desiccant cold air distribution system , 1989 .

[9]  John Murphy.  Dehumidification performance of HVAC systems , 2002 .

[10]  Jae-Weon Jeong,et al.  Energy Conservation Benefits of a Dedicated Outdoor Air System with Parallel Sensible Cooling by Ceiling Radiant Panels , 2003 .

[11]  Renato Lazzarin.  La deumidificazione chimica fra teoria e pratica , 2002 .

[12]  M. K. Khattar.  Critical supermarket issues , 1998 .

[13]  Donald P. Gatley.  Dehumidification enhancements for 100-percent-outside-air AHUs, Part 3 , 2000 .

[14]  B. W. Olesen.  International development of standards for ventilation of buildings , 1997 .

[15]  Hr Trechsel,et al.  Moisture control in buildings , 1994 .

[16]  B. Kovak,et al.  The Sanitizing Effects Of Desiccant-Based Cooling , 1997 .

[17]  D. Novosel,et al.  Advances in desiccant technologies , 1996 .

[18]  D. B. Shirey,et al.  Dehumidification issues of Standard 62-1989 , 1998 .

[19]  J. E. Janssen,et al.  Ventilation for acceptable indoor air quality , 1989 .

[20]  Stanley A. Mumma,et al.  Designing Dedicated Outdoor Air Systems , 2001 .

[21]  W. Kessling,et al.  Energy storage in open cycle liquid desiccant cooling systems , 1998 .

[22]  L. G. Harriman.  The basics of commercial desiccant systems , 1994 .

[23]  William A. Beckman,et al.  Open-cycle desiccant air conditioning as an alternative to vapor compression cooling in residential applications , 1984 .

[24]  M. Meckler.  Desiccant-assisted air conditioner improves IAQ and comfort , 1994 .

[25]  K. Mcgahey,et al.  New commercial applications for desiccant-based cooling , 1998 .

[26]  Shan K. Wang,et al.  Handbook of Air Conditioning and Refrigeration , 1993 .

[27]  L. Harriman,et al.  Dehumidification equipment advances , 2002 .

[28]  J. W. Spears,et al.  Gas-fired desiccant system for retail super center , 1997 .

[29]  B. K. Hodge,et al.  Thermodynamic assessment of desiccant systems with targeted and relaxed humidity control schemes , 1998 .

[30]  K. W. Crooks,et al.  Controlling rotary desiccant wheels for dehumidification and cooling , 1996 .

[31]  Laura Bellia,et al.  AIR CONDITIONING SYSTEMS WITH DESICCANT WHEEL FOR ITALIAN CLIMATES , 2000 .

[32]  W. A. Beckman,et al.  Hybrid desiccant cooling systems in supermarket applications , 1985 .

[33]  V. C. Mei,et al.  An assessment of desiccant cooling and dehumidification technology , 1992 .

[34]  Laura Bellia,et al.  Outdoor‐air design conditions relating to the capacity of air‐conditioning systems , 2000 .

[35]  Lew Harriman,et al.  Humidity Control Design Guide for Commercial and Institutional Buildings , 2001 .