In addition to main elements (a compressor and heat exchangers) the refrigeration unit scheme also includes the ancillary equipment: linear, protective, circulating and drain receivers, liquid separators, oil separators, refrigerant and cooling medium circulation pumps, air purgers and others.
Heat exchangers considerably identify RM weight-size and energy parameters. Heat exchangers weight amounts to 50-70% on average in a total weight of ammonia refrigerating machines (APMs) equipment.
The technical-and-economic indexes of refrigerating machine operation are substantially determined by compressor unit performance indexes.
A compressor unit comprises the following:
The choice of a refrigerating machine cycle particularly depends on the required temperature of the flow to be cooled (the temperature maintenance in a cooling chamber) and on the ambient temperature. A type of compressor and heat exchangers, a working substance and a plant scheme itself have a substantial influence on the cycle.
The ammonia (NH3) is the most advanced among natural substances, which are used as working media in refrigeration units, and known under designation R717. Below we shall consider positive and negative properties of the ammonia using as a refrigerant in comparison with freons.
Technical proposal is developed when it is stipulated in technical specifications.
Technical proposal is worked out with the aim of revealing the additional or specified requirements to the product (technical characteristics, quality parameters and others) which could not be given in technical specifications and it is reasonable to give them on the basis of preliminary design study and analysis of product different variants.
Technical design is developed when it is stipulated in technical specifications, the protocol of technical proposal or sketch design review.