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General information about the cooling systems, refrigeration machines and installations

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<strong>Refrigeration plants and installations</strong>

Purchasing process consumers cold is provided by refrigeration or cooling stations.
Refrigeration plant - is a separate building on the master plan of the enterprise. It is intended to supply a cold consumers several parameters (temperatures) in the range from 7 up to -25 ° C.
Cooling stations are central and craft. They are part of the main energy service company. The station is multiple chillers - at least one for each temperature.
Refrigerator - usually located in the technology workshop and is an integral part of the process equipment of primary production. It is designed to provide a single production cold one parameter, usually cold below -25 ° C, and is subject to service of the Chief Technologist.

<strong> Classification chillers</strong> (XM)

XM classification (International Classification - this installation class R) is made on different grounds.

1. Depending on the type of physical process, which produces cold, XM is divided into the following types:
a) refrigerating machines using the phase transition of the propellant (HA) from a liquid to a vapor. These include vapor compression, absorption, ejector XM;
b) chillers using enlargement processes with production of external work. This air expander machine, so-called Turbo-refrigerating machine (CTC);
c) using XM enlargement process without the production of air (Ranque-Hilsch). This vortex air chillers;
d) XM using the Peltier effect. This thermoelectric coolers.

2. Depending on the kind of energy distinguish chillers
a) using mechanical energy (compression chillers with electric and turbine drives);
b) heat-(and ejector absorption chillers);
c) direct use of electrical energy (thermoelectric refrigerating machines).

3. Depending on the scheme and the type of thermodynamic cycle are distinguished: one-, two-, and multi-cascading and chillers;

4. According to distinguish the following modes of operation XM:
a) high-temperature - with t0> -10 ° C. This air conditioning systems XM (usually single-);
b) Mean - t0 to -10 to -30 ° C (one-and two-stage compressors);
c) low temperature - from t0 below -30 ° C. It usually multistage cascading and XM.

5. Depending on the purpose of distinction - universal and specialized XM.

6. In depending on the working fluid XM divided into ammonia, freon, propane, air, steam-, water-ammonia, lithium bromide, etc.

7. Сompressor chillers type compressor used subdivided into reciprocating, rotary, centrifugal, ejector, etc.
Advantages and disadvantages of XM. Their application

1) XM <strong>vapor compression piston compressors</strong>. They were widely spread in everyday life, trade, catering, industry.

Pros:

- They have the highest energy performance (efficiency, coefficient of performance);
- These machines greatest pressure ratio Pk condensation and boiling P0, and therefore, the greatest temperature difference between Tc and T0.
disadvantages:
-limited performance;
-increased level of vibration;
-less reliable than machines with screw and centrifugal compressors (wear and the risk of water hammer).
2) <strong>XM centrifugal vapor compression (and axial) compressor</strong>s. They find application in all industries where large capacity. Especially in the chemical, petrochemical, gas industries.
Pros:
-have a large, virtually unlimited, cooling capacity;
-have small specific indicators of metal, size;
-High reliability;
-comfortable in the regulation;
-well balanced (low vibration, small foundation).
disadvantages:
low energy efficiency at low cooling capacity (less than 700 kW).

3) <strong>XM screw oil-injected compressors.</strong>
Pros:
-highly reliable, are not afraid of water hammer;
-have a satisfactory energy performance when operating at design conditions;
-well balanced, does not require foundation;
-easy to control.
disadvantages:
-on any modes remains unchanged pressure ratio of the compressor. This reduces performance on off-design operating conditions; -Availability bulky metal capacity of the oil system;
-noise operation.
XM with screw compressors are widely used in the range of capacities from 60 to 700 kW, ie at the junction between the piston and XM centrifugal compressors.

4) <strong>Absorption chillers</strong>.
Pros:
-it is possible to use low-value heat from the low potential (the secondary side and the energy);
-simple, reliable in operation;
convenient in-regulation, low noise;
-can be placed in an open area.
disadvantages:
-awkwardness, of metal;
low-energy performance.

5) <strong>The ejector chillers</strong>.

This steam-XM, so the temperature gets cold is positive, ie T0> 0. Used in air conditioning systems in the presence of low-grade steam or cheap to boot selections CHP heating in summer.
Advantages the same as that of the absorption XM except quietness.
disadvantages:
- Low energy efficiency;
- Noise.

6) <strong>Air expander XM</strong> (CTC).
Pros:
- Safe;
- Easy to operate, compact;
- High energy efficiency in the design range of temperatures.
Disadvantages: lack of energy efficiency at temperatures above gets cold -80 ° C and at low cooling capacity (less than 10 kW).
Operating temperature range -80 ^ -100 ° C, with cooling capacities up to 30 kW (CTC 1-25 Kazan Compressor Plant). Several foreign designs have a range of -120 to -150 ° C.
Used in the food industry, climatic testing machines and mechanisms, with a variety of materials, etc. [3].

7) <strong>Air vortex XM.</strong>
Pros:
- Extremely simple;
- Reliable;
- Safe in operation.
disadvantages:
- Low energy efficiency;
- Noise;
- Small cooling capacity (up to 3 kW).
Application of vortex tubes is often advantageous when a single or episodic short-term needs in the cold: in the truck; in the metal; in protective suits; in medicine, etc.

8) <strong>Thermoelectric coolers.</strong>
Simple, convenient, reliable, noiseless, but they have large upfront costs and low energy efficiency.
Currently there are no procedures for the selection of type chiller that takes into account all the factors specific conditions. Therefore, the most effective choice can only be made on the basis of technical and economic comparison of options under comparable conditions. Can serve as a criterion of comparison given the costs, unit costs of energy, the cost per unit of delivered cold.......

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