Danfoss AKVA 10, AKVA 1, AKVA 20 Data sheet

Data Sheet

Electric expansion valves Type AKVA 10, AKVA 15 and AKVA 20

Designed for ammonia refrigerating plant

AKVA are electric expansion valves designed for ammonia refrigerating plant.

The AKVA valves are normally controlled by a controller from Danfoss’ range of ADAP-KOOL controllers.

The AKVA valves are supplied as a component programme, as follows:

• Separate valve

• Separate coil with terminal box or cable

• Spare parts in the form upper part, orice and

lter

The individual capacities are indicated with a number forming part of the type designation. The number represents the size of the orice of the valve in question.

A valve with orice 3 will for example be designated AKVA 10-3.

The orice assembly is replaceable.

Features

• The valve requires no adjustment

• Wide regulation range

• Replaceable orice assembly

• Wide range of coils for d.c. and a.c.

• Quick reaction in whole range of stated capacity.

• In some applications AKVA can be used both as expansion valve and solenoid valve.

• Classication: DNV, CRN, BV, EAC etc. To get an updated list of certication on the products please contact your local Danfoss Sales Company.

AI183786440857en-000801

Electric expansion valves, Type AKVA 10, AKVA 15 & AKVA 20

Functions

The valve capacity is regulated by means of pulse-width modulation. Within a period of six seconds a voltage signal from the controller will be transmitted to and removed from the valve coil. This makes the valve open and close for the ow of refrigerant.

Figure 1: Function

The relation between this opening and closing time indicates the actual capacity. If there is an intense need for refrigeration, the valve will remain open for almost all six seconds of the period. If the required amount of refrigeration is modest, the valve will only stay open during a fraction of the period. The amount of refrigeration needed is determined by the controller. When no refrigeration is required, the valve will remain closed.In some applications, AKVA can advantage-ously be used both as expansion valve and solenoid valve. See Applications

Electric expansion valves, Type AKVA 10, AKVA 15 & AKVA 20

Applications

Recommendations

It is important to realize when AKVA is operating, that the valve always is fully open or fully closed. That means that this way of operation should always be considered during the refrigeration design. (Piping, liquid velocity, sub cooling etc.)

Danfoss have the following recommendations/guidelines to be taken into considerations:

• In 1:1 applications (1 evaporator, 1 condenser and 1 compressor) chillers with a small amount of refrigerant or installed in front of a Plate Heat Exchangers, it must be observed that every time the AKVA is fully open or closed it will have a signicant impact on the hole system. (e.g. pressure variations on suction side). Please observe that the performance of such a system is not only related to one component. (e.g. AKVA) Other factors which is very important to include in the overall refrigeration system design:

◦ Liquid distribution at and design of evaporator ◦ total evaporator coil is of adequate length thus superheat can be controlled within the entered period time

(normal 6 sec. or 3 sec.)

◦ mounting principle of temperature sensor, to ensure a steady and fast signal can be detected by the electronic

system.

• If pressure dependent valves like, ICS with pilots like CVP e.t.c., is installed between evaporator and compressor, it can eect the lifetime of ICS, because the piston of the ICS will operate together with operation of AKVA. Type of refrigerant and evaporator has a big inuende of the size of pulsations after the evaporator and in front of the ICS.

• AKVA is a direct pressure independent valve. That means that if non-Danfoss electronic controllers is used, intelligent and fast optimal control is needed, because the quick pressure changes only can be detected and compensated via the electronic control system.

• Liquid lines must be designed according to AKVA capacity and not evaporator capacity.

• To avoid ash-gas ensure sucient sub-cooling or design liquid lines thus to big pressure drop is avoided, when AKVA is open. If not sucient subcooling is not obtained (normally 4K) it will have an impact on the lifetime of the vale).

• Where the demand for safety level is extremely high, (e.g. Liquid Level Control in a pump seperator) an extra valve can be installed in front of AKVA to avoid leakage. This valve must be Danfoss type EVRAT.

• Always install a 100 µm lter in front of AKVA 15 and AKVA 20 valves.

• If AKVA has to be used in chillers. Please contact Danfoss.

Electric expansion valves, Type AKVA 10, AKVA 15 & AKVA 20

Media

Refrigerants

For R717 (Ammonia) and R744 (CO2)

New refrigerants

Danfoss products are continually evaluated for use with new refrigerants depending on market requirements.

When a refrigerant is approved for use by Danfoss, it is added to the relevant portfolio, and the R number of the refrigerant (e.g. R513A) will be added to the technical data of the code number. Therefore, products for specic refrigerants are best checked at store.danfoss.com/en/, or by contacting your local Danfoss representative.

1.2.3.4.5.6.7.8.9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

Inlet

Outlet

Orice

Filter

Valve seat

Armature

Aluminium gasket

Coil

DIN plug

Filter

Cover

Valve body

Spring

Orice assembly

O-ring

Piston assembly

Pilot orice

Pilot valve

Valve type

AKVA 10

AKVA 15

AKVA 20

Tolerance of coil voltage

+10 / -15%

Enclosure to IEC 529

Max. IP 67

Working principle (Pulse-width modulation)

PWM

Recommend period of time

6 seconds

Capacity (R717)

4 to 100 kW

125 to 500 kW

500 to 3150 kW

Regulation range

10 - 100%

Connection

Weld

Media temperature

- 50 to 60 °C

- 40 to 60 °C

Ambient temperature

- 50 to 50 °C

- 40 to 50 °C

Leak of valve seat

< 0.02% of kv-value

MOPD

18 bar

22 bar

18 bar

Filter

Internal 100 µm replaceable

external 100 µm

Max. working pressure

PS = 42 bar

Electric expansion valves, Type AKVA 10, AKVA 15 & AKVA 20

Product specication

Design

Figure 2: AKVA 10 Figure 3: AKVA 15 Figure 4: AKVA 20

The AKVA 10 valves covers a capacity range from 4 kW to 100 kW (R 717) and are divided into 8 capacity ranges. The AKVA 10 valve bodies are made in stainless steel and have weld connections.. The AKVA 15 valves covers a capacity range from 125 kW to 500 kW (R 717) and are divided into 4 capacity ranges. The AKVA 15 valves have ange connections. The AKVA 20 valves cover a capacity range from 500 kW to 3150 kW (R 717) and are divided into 5 capacity ranges. The AKVA 20 valve has weld connections.

The AKVA valves can be used for:

• Flooded evaporation (high/low pressure)

• Pump separators

• Direct expansion. See Applications.

If AKVA has to be used in chillers please contact Danfoss.

Table 1: Technical data

Valve type

Capacity in kW at pressure drop across valve ∆p bar

2468101214

AKVA 10 - 1

2.2

3.1

3.7

4.1

4.4

4.755.2

AKVA 10 - 2

3.5

4.9

5.8

6.577.5

7.9

8.3

AKVA 10 - 3

5.6

7.7

9.1

10.2

11.1

11.9

12.5

13.1

AKVA 10 - 4

9.1

12.4

14.7

16.5

17.9

19.2

20.2

21.1

AKVA 10 - 5

14.2

19.4

22.9

25.72829.9

31.6

AKVA 10 - 6

31.2

36.4

41.44548.1

50.7

53.1

AKVA 10 - 7

36.6

49.3

58.16570.6

75.3

79.4

AKVA 10 - 8

59.1

78.9

93.5

104

112

120

126

131

AKVA 15 - 1

95.7

113

127

138

148

156

163

AKVA 15 - 2

153

181

203

221

236

250

261

AKVA 15 - 3

231

274

308

335

358

377

395

AKVA 15 - 4

383

455

510

555

593

625

655

AKVA 20 - 1

383

455

510

555

593

625

655

AKVA 20 - 2

612

726

814

886

947

999

1045

AKVA 20 - 3

959

1137

1275

1388

1482

1564

1635

AKVA 20 - 4

1552

1836

2057

2239

2391

2523

2639

AKVA 20 - 5

2479

2921

3267

3550

3789

3994

4174

Correction factor

2K4K10K

15K

20K

25K

30K

35K

40K

45K

50K

R717

1.01

1.00

0.98

0.96

0.94

0.92

0.91

0.89

0.87

0.86

0.85

Electric expansion valves, Type AKVA 10, AKVA 15 & AKVA 20

Capacity

Range: - 40 °C to 10 °C

Table 2: R717

Correction for subcooling

The liquid injected capacity must be corrected, if the subcooling deviates from 4 K. Use the actual correction factor indicated in the table. Multiply the liquid injected capacity by the correction factor to obtain the corrected capacity.

Table 3: Correction factors for subcooling ∆t

sub

Dimensioning

To obtain an expansion valve that will function correctly under dierent load conditions it is necessary to consider the following points when the valve has to be dimensioned.

These points must be dealt with in the following sequence:

Evaporator capacity

Pressure drop across the valve

Correction for subcooling

Correction for evaporating temperature

Determination of valve size

Correctly dimensioned liquid line

Example for a direct expansion system

Evaporator capacity

The evaporator capacity is found in the specications from the evaporator supplier.

Pressure drop across the valve

The pressure drop across the valve directly determines the capacity and must therefore be considered. The pressure drop across the valve is normally calculated as the condensing pressure minus the evaporating pressure and other pressure drops in the liquid line, distributor, evaporator, etc. It is indicated in the following formula: ∆pvalve = pc – (pe + ∆p1 + ∆p3 + ∆p4)

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