Updated: July 2002

1. Outline

In the refrigeration and storage field, ammonia has been used since old times as a refrigerant. It is an environmentally friendly refrigerant with an ozone depletion potentiant (ODP) and a global warming potential (GWP) of zero and has an excellent coefficient of performance (COP).
Its noted disadvantages are toxicity, odor, and flammability and, therefore, its use in Japan had been limited. However, these disadvantages have been overcome by minimizing the refrigerant charge and elimination of leakage of the refrigerant to the outside.

2. Features

Conventional refrigerating machines used oil insoluble in ammonia. A flooded-evaporator holding much refrigerant was therefore used. By the development oil which is soluble in ammonia (polyalkylene glycol), a direct expansion evaporator (plate system) similar to fluorocarbon refrigerating machine can be used. The amount of refrigerant charged is minimized to 1/50 of that of conventional machines and the size of the evaporator is reduced by 40%.
As a measure against external leakage, a compressor integrated motor and high-performance shaft seal have been developed and refrigerant pipes have been tabincated in plant so as to remarkably increase the safety. Also safety is assured by reducing the refrigerant charge and providing a standard scrubber system.
In order to fully utilize the excellent refrigerant characteristics of ammonia, with optimized refrigerant flow and stasee automatic operation an electronic expansion valve (small superheat control) and a microprocessor control panel were developed.
Recently, a brine cooler unit (shown in the photo below) in which the refrigerant piping is within the machine case and an evaporation type condenser used to increase the COP has become the mainstream, eliminating on-site refrigerant piping work.

3. Scope of Application

The ammonia-refrigerator, which has been mainly used in industrial refrigeration and storage, was recognized as safe since it was adopted for all skate rinks of the Nagano Olympics held in 1998, and is surely improving its reputation mainly in the food market. The production control of HCFC22 will start in 2004, and it is expected that use of ammonia as an alternate will be promoted.