Refrigerant charge Levels

8.7 References

IPCC/TEAP, 2005 IPCC and TEAP, Special Report on Safeguarding the Ozone Layer and the Global Climate System, Issues Related to Hydrofluorocarbons and Perfluorocarbons, Intergovernmental Panel on Climate Change Technology and Economic Assessment Panel, 2005.

JARN, 2013/08 The Japan Refrigeration and Air Conditioning Industry Association; Heat Pumps overview, August, 2013

Neskå, 1998 Nekså, P., Rekstad, H., Zakeri, G.R. and Schiefloe, P.A.: CO₂ – heat pump water heater: characteristics, system design and experimental results, Int. J. Refrig. Vol. 21, No. 3, pp.172-179, 1998

Neskå, 2002 Nekså, P: CO₂ Heat Pumps, International Journal of Refrigeration, Vol 25, Issue 4, June 2002, p 421-427, 2002

Neskå, 2010 Nekså, P., Walnum, H. and Hafner A.: CO₂ - A refrigerant from the past with prospects of being one of the main refrigerants in the future, 9th IIR Gustav Lorentzen Conference 2010, Sydney, April 12-14, ISBN 978-2-913149-74-8, ISSN 0151-1637, 2010

Palm, 2008 Palm, B. (2008) Hydrocarbons as refrigerants in small heat pump and refrigeration systems-a review, Int. J. of Refrigeration 31, 2008

Shigehara, 2001 T Shigeharu, Y Ryuzaburo, K Shigeru, (2001) The Performance Evaluation of Room Air Conditioner using R32 In the Case of Cooling and Heating Mode, Trans JSRAE, Vol.18; No.3.

Stene, 2008 J. Stene, SINTEF Energy Research, Department of Energy Processes, Norway, CO₂ Heat Pump System for Space Heating and Hot Water Heating in Low-Energy Houses and Passive Houses, 8th IIR Gustav Lorentzen Conference on Natural Working Fluids September 7-10, 2008

Yajima, 2000 R. Yajima, K. Kita, S. Taira, N. Domyo R32 as a solution for energy conservation and low emission , IIR 2000 Purdue

Martin Dieryckx

Dennis Dorman

Mohamed Alaa Olama

Andy Pearson

9 Chillers

9.1 Introduction

Chillers commonly employ a vapour compression cycle using reciprocating, scroll, screw, or turbo (centrifugal or mixed axial/centrifugal flow) compressors. Heat typically is rejected through air-cooled or water-cooled heat exchangers. Evaporatively-cooled condensers and dry coolers also can be used for heat rejection. Though less common, an absorption refrigeration cycle is used in absorption chillers, especially where a low-cost source of hot water or steam is available.

Chillers tend to stay in service for long periods in the range from 20 to 40 years. Even though CFCs were phased out for new equipment in 2010, a significant number of CFC-11, CFC-12, and HCFC-22 chillers are still operating. HCFC-123 also is used, but will be phased out in 2020. Article 5 countries may still use all these refrigerants. The change-over to zero ODP refrigerants required a very high investment and was a lengthy process. However, the current generation of chillers has proven to be highly reliable and has resulted in higher performance, no small feat.

The zero ODP refrigerants used today generally have GWPs greater than 1000. Climate change concerns are driving efforts to seek lower-GWP refrigerants to replace the refrigerants currently in use, mainly HFC-134a and R-410a. Also, Article 5 countries are expressing interest in “leap-frogging” to the next generation of refrigerants in order to avoid investing in technology that may become obsolete.

While manufacturers, consumers, and regulators alike have an interest in low GWP refrigerants, a number of things stand in the way. This chapter presents refrigerants under consideration and factors affecting their success. In the end, the time and expense to change to another generation of refrigerants likely will be required again.

All other considerations aside, to be acceptable, new refrigerants should result in products with energy efficiencies that are equal to or better than the refrigerants replaced. This is because the global warming effects from chillers are dominated by the energy-related component from their power usage. Life Cycle Climate Performance (LCCP) models typically show that more than 95% of the climate effect is due to energy consumption. The direct global warming effects from refrigerant emissions are significantly smaller. Emissions have been significantly reduced in recent years through lower charge systems, low-leak designs, manufacturing and testing improvements, and improved service practices. At the same time, chiller energy efficiency has been enhanced in today’s systems by adding features such as variable speed drives, economizers, suction line heat exchangers, and increased subcooling. The use of higher performing chillers is more important to climate change than prematurely changing to another intermediate refrigerant solution.

Fortunately, the consumer can make intelligent choices when alternatives are explored. The annual energy consumption can be calculated with computer simulation programs using the chiller(s) load profile, building loads, and weather data. For large and complex chiller systems, extensive modeling can provide systems and chiller solutions that minimize total energy consumption. However, smaller machines are commonly sold on the basis of full and/or part load rating, a simplified representation of energy consumption. Rating standards and rating certification programs exist in most countries. AHRI Standard 550/590 (AHRI 2011) and EN 14825 are among the rating standards in use.
Other methods used to describe the environmental effects of chiller operation are Total Equivalent Warming Impact (TEWI) or Life Cycle Climate Performance (LCCP). These methods are defined in Chapter 2, Refrigerants, and further discussed in Chapter 11, Sustainable Refrigeration. The ozone depletion potential (ODP) and global warming potential (GWP) of the refrigerants mentioned in this chapter are given in Chapter 2. Chapter 2 includes other refrigerant properties and a description of the issues associated with changing refrigerants, including safety aspects.