The theses from explanatory note and the examples of design documents, developed within the framework of technical design of water-cooled condensing unit ККА-24-W, are given below.

Unit reference designation – KKA-Q-W,

where

KKA – condensing unit;

Q – refrigeration capacity, kW;

W – cooling of condenser heat-exchange surface with water.

At the technical design stage the estimation of required technical characteristics and parameters, essential for specifying the equipment grades and dimension types selected within the framework of sketch design, was performed. The sketch design provides the required technical characteristics in all operation modes of the unit and, consequently, of the entire refrigeration unit equipment system, and also the selection of additional accessories necessary for providing the reliable operation of the refrigeration unit.

At the technical design stage it was decided to include the refrigeration unit control board, comprising the start-control devices for unit and air coolers control, as a component of the condensing unit. The air coolers are installed in cooling chambers serviced with this unit. The following devices were also included into the condensing unit:

protective automation devices:

• dual pressure switch KP 15 (also the names “pressure regulator” or “ pressostat” are used in technical literature). It is used for protection from condensation pressure inadmissible increase and evaporation pressure decrease;
• differential oil pressure switch MP 55;

and devices for diagnostics:

• pressure gauge for refrigerant condensation pressure measurement;
• vacuum pressure gauge for refrigerant evaporation pressure measurement.

Protective automation and diagnostics devices are now installed on the panel intended for them.

Also at the technical design stage the elements for refrigerant pipeline fixation were used to prevent the displacement, mechanical damages and vibration compensation in a discharge line.

Sight glass SGI 16s with moisture indicator was also included into the unit to perform the diagnostics of refrigerant dryness factor at filter-drier outlet.

Figure Т.1 – Unit general view approved at the technical design stage

Table Т.1 – Unit technical characteristics in nominal mode

	Parameter name	Measurement units	Value
1	Refrigeration capacity	kW	23,6
2	Refrigeration capacity*		23,6
3	Condenser capacity		34,6
4	Compressor type	-	Semi-hermetic reciprocating one
5	Compressor model		4NES-20Y
6	Refrigerant in use		R507A
7	Refrigerant evaporation temperature	°С	-15
8	Refrigerant condensation temperature		45
9	Refrigerant suction vapours temperature		20
10	Water temperature at condenser inlet		32
11	Discharge temperature without cooling		94,5
12	Liquid overcooling	K	0
13	Cooling water flow rate through condenser	m3/h	5
14	Refrigerant mass flow rate	kg/h	726
15	Power supply	-	400 V – 3 phases – 50 Hz
16	Allowable range of power supply voltage	V	380-420
17	Consumable current	A	19,8
18	Consumable power	kW	11
19	Capacity regulation degree	%	100
20	СОР/EF (efficiency factor)	-	2,14
21	СОР/EF*		2,14
22	Refrigerant amount in receiver**	kg	14,4
23	Product dry weight		375
* As per standard EN12900 (suction vapours temperature is 20°С, liquid overcooling is 0 К)
** At liquid refrigerant temperature +20°С and receiver filling volume 90%

 Table Т.2 – List of unit main elements

Element name	Designation	Manufacturer
Compressor	4NES-20Y-40P	Bitzer
Condenser	K283H
Receiver	F152H
Oil separator	OSH-409	Alco
Filter-drier	DML305s	Danfoss
Ball valve	GBC 16s
Check valve	NRV 19s
Dual pressure switch	KP 15
Differential pressure switch	MP 55

Figure Т.2 – Condensing unit ККА-24-V. Overall, connecting dimensions and arrangement.

The unit overall and connecting dimensions, main elements and assembly units layout, are shown in the Figure.

To become familiar with all design stages and examples of their performance, proceed to the review of the article “Stages of designing”.