Ashrae Journal - December 2008 - (Page 50) Refrigeration for Ships By Amey S. Majgaonkar, M.E. N aval refrigeration applications are similar to a high-rise building, only laid on its side. However, naval applications must deal with a corrosive marine environment, limited space for equipment, and the movement of the ship. This article describes the many additional constraints a designer faces in refrigeration system design for naval applications. The standards referred to in this article are case specific and can be used only after agreement with that particular navy. Usually, each navy uses standards per its own requirements on a case-by-case basis. In many cases, navies allow equivalent or similar standards for equipment and raw materials after a detailed study of project specification requirements regarding improvements in system design and operation. Calculating Refrigeration Capacity For chiller packages in most cases, a navy will specify the required capacity, or capacity can be calculated from chilled water flow rate and temperature difference. The capacity usually is in the range of 35 kW to 2,700 kW per chiller package. Refrigerant Refrigeration plants are used onboard mainly for food preservation in cold rooms and for producing ice required for 50 ASHRAE Journal onboard consumption. Heat load calculations provide the refrigeration capacity required for cold rooms. Heat load can be calculated by using methods available in technical literature or by using commercial software. The ASHRAE Handbook— Fundamentals and ISO Standard 75471 are useful for this purpose. The required capacity of a refrigeration plant is determined from individual cold-room heat load, ice production load, and from the required cooling down period. Generally, the refrigeration plant on warships has a capacity in the range of 3.5 kW to 50 kW (1 ton to 14 ton). ashrae.org In developing countries, R-22 will be phased out soon. The service life of older ships is being extended to 10 to 12 years by retrofitting them with better plants, equipment, instruments, and machines. R-12 systems are being replaced by R-22 systems because the plant size is smaller compared to an R-134a replacement system. For new ships, environmentally friendly R134a is preferred. Limited Space As stated previously, a ship is similar to a high-rise building, only laid on its About the Author Amey S. Majgaonkar, M.E., is a senior engineer at Kirloskar Pneumatic Company Limited, in Pune, India. He is a member of ISHRAE. December 2008 http://www.ashrae.org
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