26
5.7 - Minimum chilled water flow
If the system water flow rate is lower than the minimum water
flow rate, recirculation of the evaporator flow may occur. The
temperature of the mixture leaving the evaporator must
never be less than 2.5 K lower than the chilled water entering
temperature.
5.8 - Maximum chilled water flow
The maximum chilled water flow is limited by the maximum
permitted pressure drop in the evaporator. It is provided in
the tables in chapter 5.7. If the flow exceeds the maximum
value, two solutions are possible:
•
Modify the flow rate with a control valve.
• Bypass the evaporator to obtain a highter temperature
difference with a lower evaporator flow rate.
5.9 - Variable flow
A pump with variable flow can be used in these units. The
units maintain a constant leaving water temperature under
all flow conditions. For this to happen, the minimum flow
rate must be higher than the minimum flow given in the table
of permissible flow rates and must not vary by more than
10% per minute.
If the flow rate changes more rapidly, the system should
contain a minimum of 6.5 litres of water per kW instead of
the values below.
30WG
Minimum Maximum
Evaporator
Entering water temperature at start-up
°C 7.5*
27
Leaving water temperature during operation
°C
5**
20
Entering/leaving water temperature difference
K
2,5
7
Air entering temperature (at start-up and during operation)***
Air entering temperature (fixed-speed fan)
°C
0***
35 to 48‡
Air entering temperature (variable-speed fan)
°C
-10 to -20†
35 to 48‡
*
For entering water temperatures below 7.5 °C at start-up, contact Carrier.
** 30WGA unit can operate down to 0 °C if the configuration of the fluid type used
is modified. If the leaving water temperature is below 5 °C, a frost protection
solution must be used.
*** The minimum temperature range is based on the condenser selected. If
the condenser only has a few fan stages, the use of variable-speed fans is
recommended from 10 °C.
† The minimum temperature range is based on the condenser selected.
‡ The maximum temperature range is based on the condenser selected.
5.6 - Operating range 30WGA
20
25
30
35
40
45
50
55
60
65
-2
0
2
4
6
8
10 12 14 16 18 20
30WGA standard unit
30WGA unit for medium temperature application (% glycol < 25%)
Evaporator leaving water temperature, °C
Condensing
temperatre,
°C
Standard
Medium
temperature
application
5.5 - Operating limits 30WGA
5.10 - Water flow rates
5.10.1 - Standard 61WG
61WG Evaporator water flow rate, l/s
Minimum*
Minimum** Maximum***
Maximum****
Low
pressure
High
pressure
Low
pressure
High
pressure
020
1.0
0.9
0.5
3.1
3.6
3.8
025
1.0
1.0
0.5
3.3
3.8
4.1
030
1.0
1.0
0.5
3.3
3.8
4.1
035
1.1
1.1
0.6
3.6
4.2
4.7
040
1.2
1.1
0.6
3.8
4.4
5.0
045
1.2
1.1
0.8
4.0
4.6
5.4
050
1.6
1.4
0.8
5.4
7.8
9.2
060
1.5
1.6
1.0
6.1
8.0
9.9
070
1.6
1.5
1.1
6.2
8.1
10.3
080
1.6
1.5
1.3
6.3
8.3
10.9
090
2.0
1.6
1.5
7.8
8.7
12.5
*
Units with hydronic module
Flow rate for a maximum permitted temperature difference at the minimum
leaving water temperature
** Units without hydronic module
Flow rate for a maximum permitted temperature difference at the minimum
leaving water temperature
*** Units with hydronic module
Maximum flow rate for an available pressure of 20 kPa (unit with low-pressure
hydronic module) or 50 kPa (unit with high-pressure hydronic module)
**** Units without hydronic module
Maximum flow rate for a pressure drop of 100 kPa in the plate heat exchanger.
61WG Condenser water flow rate, l/s
Minimum*
Maximum**
Maximum***
Low pressure
High pressure
020
0.3
3.1
3.5
3.8
025
0.3
3.3
3.8
4.1
030
0.3
3.3
3.8
4.1
035
0.4
3.5
4.1
4.7
040
0.4
3.7
4.3
5.0
045
0.4
3.9
4.5
5.4
050
0.4
4.8
6.8
7.0
060
0.5
5.5
7.0
7.5
070
0.5
5.6
7.2
7.8
080
0.6
5.8
7.4
8.2
090
0.6
7.2
7.9
9.3
*
Units with or without hydronic module
Minimum flow rate for a water temperature difference of 18 K-
Note: Operation permitted up to a value of 20 K.
** Units with hydronic module
Maximum flow rate for an available pressure of 20 kPa (unit with low-pressure
hydronic module) or 50 kPa (unit with high-pressure hydronic module)
*** Units without hydronic module
Maximum flow rate for a pressure drop of 100 kPa in the plate heat exchanger
5.10.2 - 61WG with option 272
61WG
Minimum evaporator glycol solution flow rate - option 272*, l/s
Minimum**
Minimum***
Low pressure
High pressure
020
0.5
0.5
0.5
025
0.5
0.5
0.5
030
0.5
0.5
0.5
035
0.6
0.6
0.6
040
0.6
0.6
0.6
045
0.8
0.8
0.8
050
2.0
1.9
0.8
060
1.9
1.9
1.0
070
1.9
1.9
1.1
080
1.9
2.0
1.3
090
2.2
2.0
1.5
*
Option 272: Condenser side high-temperature water production, evaporator side
with glycol solution,
** Units with hydronic module
Minimum flow rate for a maximum permitted temperature difference at the
minimum leaving water temperature
*** Units without hydronic module
Minimum flow rate for a maximum permitted temperature difference at the
minimum leaving water temperature
Summary of Contents for 30WG 020
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