Sage Journals: Discover world-class research

Abstract

A comparison study on using air-cooled and water-cooled conventional and oil-free chillers in hospitals in Hong Kong is reported. The study commenced with a comprehensive literature review to reaffirm the effectiveness of recommended precaution measures for containing the risk of Legionnaires’ disease (LD) associated with using cooling towers. Numerical performance models for oil-free chillers established for use in the study are presented. Based on recorded cooling demands of two existing hospitals, the life-cycle energy consumption and cost of system options involving different combinations of heat rejection method and chiller type were evaluated, compared and discussed. The results show that water-cooled air-conditioning systems with conventional chillers and cooling towers are still more energy efficient than air-cooled systems with oil-free chillers. Water-cooled oil-free chillers may become an economically viable choice when their price is lowered in future. Pilot installation is recommendable, as it would allow the reliability and maintainability of the new oil-free chillers to be ascertained.

Practical applications: Findings of the literature review reaffirmed the effectiveness of measures recommended in contemporary guidelines for LD prevention, which would ease the mind of owners, designers and operation and maintenance personnel in regard of using cooling towers in hospitals. The numerical models for oil-free chillers presented in the paper are useful for evaluation of the energy consumption of this new type of chiller and for comparison with other types of chillers. The study approach described in the paper, including the energy consumption prediction and life-cycle cost evaluation methods, provides a useful framework for similar studies.

Get full access to this article

View all access options for this article.

References

Yik

FWH

Burnett

Prescott

. Predicting air-conditioning energy consumption of a group of buildings using different heat rejection methods. Energy and Buildings 2001; 33(2): 151–166.

WHO. Legionella and the prevention of legionellosis 2007; Geneva,, World Heath Organization.

McCoy

. Preventing legionellosis. ASHRAE Journal, 2006; 48: H26–H32.

McQuay. Efficient, quiet and oil-free – frictionless chiller technology sets new standard for efficiency and quiet operation. Bulletin, McQuay International, 2005. Available at: www.mcquay.com (accessed 17 December 2003).

Newsletter Issue 156, April 2008. Hongkong: Electrical and Mechanical Services Department, 2008.

Business Plus. Hongkong: CLP Power Co. Ltd., 2009. Available at: https://www.clponline.com.hk/MyBusiness/greenplus/CLP_20091204/e-news_issue3_2009_e_out.pdf (accessed 6 May 2011)..

Australian/New Zealand Standard 3666 Part 3. Air-handling and water systems of buildings – Microbial control Part 3: Performance based maintenance cooling water systems 2000; Manchester, UK, Legionella Control International.

ASHRAE Standards Committee. ASHRAE Guideline 12-2000 – Minimizing the risk of legionellosis associated with building water systems 2000; Tullie Circle, NE, Atlanta, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

Health and Safety Executive. The HSEapproved code of practice and guidance2000 – Legionnaires’ disease, Thecontrol of legionella bacteria in water systems 2000; UK, Health and Safety Executive.

10.

CIBSE. CIBSE technical memorandum TM 13: Minimizing the risk of Legionnaires’ disease 2002; UK, Chartered Institution of Building Services Engineers.

11.

Sehulster

Chinn

RYW

. CDC guidelines for environmental infection control in health-care facilities 2003; US, Centres for Disease Control and Prevention.

12.

Electrical and Mechanical Services Department - The Government of Hongkong Special Administration. Code of practice for water-cooled air conditioning systems; Part 1: Design, installation and commissioning of cooling towers; Part 2: Operation and maintenance of cooling towers; and Part 3: Water treatment methods for cooling towers 2006; Hongkong, Electrical and Mechanical Services Department.

13.

Electrical and Mechanical Services Department - The Government of Hongkong Special Administration. Scheme for wider use of fresh water in evaporative cooling towers for energy-efficient air conditioning systems 2008; Hongkong, Electrical and Mechanical Services Department.

14.

American Standard Companies. Trane introduces oil-free chiller, Washington, DC, 2002.

15.

Yik

FWH

Lam

VKC

. Chiller models for plant design studies. Building Services Engineering Research and Technology 1998; 19(4): 233–241.

16.

Yik

FWH

Burnett

. BECON: A program for predicting building energy consumption for air-conditioning buildings. Transactions 1998; 5(3): 89–94.

17.

Underwood

Yik

FWH

. Modelling methods for energy in buildings 2004; Oxford, Blackwell Science.

18.

Electrical and Mechanical Services Department - The Government of Hongkong Special Administration. Code of practice onenergy efficiency of air conditioning installations 2007; Hongkong, ElectricalandMechanical Services Department.

19.

Task Group - Performance Based Methods for Service Life Prediction. (2004). CIB W080/RILEM 175 SLM service life methodologies: Prediction of service life for buildings and components. State of Art Reports, CIB.

20.

Tam LS, Lau KC, Shek LC. Achievements and participation of the pilot scheme for fresh water evaporative cooling towers: Proceedings of Symposium on Solution, Breakthrough & Technical Approach for Wider User of Water-cooled Air Conditioning System in Hong Kong, 8 December, Hong Kong Association of Energy Engineers, 2006: 1–9.

A case study on the application of air- and water-cooled oil-free chillers to hospitals in Hong Kong

Abstract

Get full access to this article

References