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All small refrigeration machines manufactured in our country are freon. To work on other refrigerators, they are not serially produced.

Fig.99. Scheme of the refrigeration machine IF-49M:

1 - Compressor, 2 - Condenser, 3 - Temperators, 4 - Evaporators, 5 - Heat Exchanger, 6 - Sensitive Cartridges, 7 - Pressure Relay, 8 - Waterguiding Gate, 9 - Desiccant, 10 - Filter, 11 - Electric Motor, 12 - magnetic switch.

Small refrigeration machines are based on the above-mentioned freon compressor capacitor aggregates of appropriate performance. Industry produces small refrigeration machines mainly with aggregates with a capacity of 3.5 to 11 kW. These include IF-49 machines (Fig. 90), IF-56 (Fig. 100), Hm1-6 (Fig. 101); CMV1-6, hm1-9 (Fig.102); CMV1-9 (Fig.103); machines without special brands with ACF-4M aggregates (Fig.104); AFV-6 (Fig.105).

Fig.104. Scheme of a refrigeration machine with AFV-4M aggregate;

1 - CAP-4M capacitor, 2 - heat exchanger TF-20M; 3 - Waterguading valve BP-15, 4 - pressure switch RD-1, 5 - compressor FV-6, 6 - electric motor, 7 - Filter-desiccant OFF-10A, 8 - Evaporators IRSN-12,5M, 9 - thermostatic valves TRV -2m, 10 - sensitive cartridges.

In significant quantities, there are also machines with aggregates of SU-2.8, FAQ-0,7e, Fax-1,1 and Fava-1.5M.

They integrate all these machines for direct cooling of stationary refrigeration chambers and various trading refrigeration equipment Public catering and food stores.

As evaporators, used ribbed ribbed coil batteries of IRSN-10 or IRSN-12.5 are used.

All machines are fully automated and completed with thermostatic valves, pressure switch and water-regulating valves (if the machine with water cooling condenser). Relatively large of these machines - hm1-6, CMV1-6, hm1-9 and CMV1-9 - supply, in addition, solenoid valves and camera temperature relays, one common solenoid valve is installed on the reinforcement shield in front of the liquid collector, with which you can Disable Freon's feed into all evaporators immediately, and chamber solenoid valves - on pipelines supplying liquid freon to cooling devices. If the cameras are equipped with several cooling devices and the Freon feeds in them are produced in two pipelines (see schemes), the solenoid valve is put on one of them, so that it is not all cooling chamber cooling devices through this valve, but only those that it feeds.

Refrigerator aggregate

The IF-56 unit is designed to cool the air in the refrigeration chamber 9 (Fig. 2.1).

Fig. 2.1. Refrigerated installation IF-56

1 - compressor; 2 - electric motor; 3 - fan; 4 - Receiver; 5 -Conacitor;

6 - filter-desiccant; 7 - choke; 8 - evaporator; 9 - Refrigerated Camera

Fig. 2.2. Cycle refrigeration Installation

In the process of throttling of liquid freon in choke 7 (process 4-5 V pH-Diagram) It partially evaporates, the main evaporation of freon occurs in the evaporator 8 due to the heat taken from the air in the refrigeration chamber (the isobaro-isothermal process 5-6 p. 0 = const. and t. 0 = const.). Preheated steam with temperature enters the compressor 1, where it is compressed from pressure p. 0 to pressure p. K (polytrophic, valid compression 1-2d). In fig. 2.2 also depicted theoretical, adiabatic compression 1-2 A s. 1 = const.. In the condenser 4, the freon pairs are cooled to the condensation temperature (process 2D-3), then condensed (isobaro-isothermal process 3-4 * when p. K \u003d. const. and t. K \u003d. const.. In this case, liquid freon is hypocheated to a temperature (process 4 * -4). Liquid freon flows into the receiver 5, from where through the filter-desiccant 6 enters the choke 7.

Technical data

Evaporator 8 consists of finned batteries - convectors. Batteries are equipped with choke 7 with thermostatic valve. Condenser 4 with forced air cooled, fan performance V. B \u003d 0.61 m 3 / s.

In fig. 2.3 shows a valid cycle of a parocompression refrigeration unit, built according to its test results: 1-2A - adiabatic (theoretical) compression of the steam of the refrigerant; 1-2D - action-visible compression in the compressor; 2D-3 - the isobaric cooling of the vapor to
Condensation temperature t. TO; 3-4 * - the isobaro-isothermal condensation of the steam of the refrigerant in the condenser; 4 * -4 - condensate undercooling;
4-5 - throttling ( h. 5 = h. 4) as a result of which the liquid refrigeration agent partially evaporates; 5-6 - isobaro-isothermal evaporation in the evaporator refrigeration chamber; 6-1 - isobaric overheating of a dry saturated pair (point 6, h.\u003d 1) to temperature t. 1 .

Fig. 2.3. Refrigeration cycle in pH-Diagram

Performance features

Basic operational characteristics Refrigeration installation are cooling capacity Q.Power consumption N., Refrigeratory consumption G. and specific cooling capacity q.. Cooling capacity is determined by the formula, kW:

Q \u003d Gq \u003d G(h. 1 – h. 4), (2.1)

where G. - consumption of the refrigerant, kg / s; H. 1 - enthalpy couple at the exit from the evaporator, KJ / kg; h. 4 - enthalpy of a liquid refrigerant before choke, KJ / kg; q. = h. 1 – h. 4 - specific cooling capacity, kJ / kg.

Also used specific volume Cooling capacity, KJ / M 3:

q. V \u003d. q / V. 1 = (h. 1 – h. 4)/v. 1 . (2.2)

Here v. 1 - Specific volume of steam at the exit of the evaporator, M 3 / kg.

The consumption of the refrigerant is located according to the formula, kg / s:

G. = Q. To / ( H. 2D - h. 4), (2.3)

Q. = c.’ PM V. IN ( t. AT 2 - t. IN 1). (2.4)

Here V. B \u003d 0.61 m 3 / s - the performance of the fan, cooling capacitor; t. IN 1 , t. B2 - air temperature at the inlet and outlet of the condenser, ºС; c.’ PM. - average bulk isobar air heat capacity, kJ / (m 3 · k):

c.’ PM. = (μ c pm.)/(μ v. 0), (2.5)

where (μ. v. 0) \u003d 22.4 m 3 / kmol - the volume of kilo praying air under normal physical conditions; (μ. c pm.) - The average isobaric molar heat capacity, which is determined by the empirical formula, KJ / (Kolol · K):

(μ c pm.) \u003d 29,1 + 5,6 · 10 -4 ( t. B1 +. t. AT 2). (2.6)

Theoretical power of adiabatic compression of the steam of the refrigerant in the process of 1-2 A, kW:

N. A \u003d. G./( H. 2a - h. 1), (2.7)

Relative adiabatic and actual cooling capacity:

k. A \u003d. Q./N. BUT; (2.8)

k. = Q./N., (2.9)

presenting heat transmitted from a cold source to hot, per unit theoretical power (adiabatic) and valid (electrical power of the compressor drive). The refrigeration coefficient has the same physical meaning and is determined by the formula.

The IF-56 unit is designed to cool the air in the refrigeration chamber 9 (Fig. 2.1). The main elements are: Freonal piston compressor 1, air cooling capacitor 4, choke 7, evaporative batteries 8, filter-drier 6, filled with moisture absorber - silicogel, receiver 5 for condensate collection, fan 3 and electric motor 2.

Fig. 2.1. Scheme of the refrigeration unit IF-56:

Technical data

The evaporator 8 consists of two ribbed batteries - convectors. Batteries are equipped with choke 7 with thermostatic valve. Condenser 4 with forced air cooled, fan performance

VB \u003d 0.61 m3 / s.

In fig. 2.2 and 2.3 shows a valid cycle of a parocompression refrigeration unit, built according to its test results: 1 - 2a - adiabatic (theoretical) compression of the steam of the refrigerant; 1 - 2D - action-visible compression in the compressor; 2D - 3 - the isobaric cooling of the vapor to

condensation temperature TK; 3 - 4 * - the isobaro-isothermal condensation of the steam of the refrigerant in the condenser; 4 * - 4 - condensate undercooling;

4 - 5 - throttling (H5 \u003d H4), as a result of which the liquid refrigeration agent is partially evaporated; 5 - 6 - isobaro-isothermal evaporation in the evaporator of the refrigeration chamber; 6 - 1 - isobaric overheating of a dry saturated pair (point 6, x \u003d 1) to T1 temperature.