Sizing The Heat Exchanger, Primary Circuit/Separating Heat Exchanger; Cooling Water - Viessmann VITOCAL 300-G Technical Manual

Design information

Sizing the heat exchanger, primary circuit/separating heat exchanger

10 °C 8 °C
A B
6 °C 4 °C
A Water
B Brine (antifreeze mixture)
Selection list for plate heat exchangers for water/water heat pumps
Heat pump Refrigerating
capacity
Type kW
Single stage heat pump
WW 121
WW 129
WW 145
Two-stage, both stages with the same output
WW+BWS
121+121
WW+BWS
129+129
WW+BWS
145+145
Two-stage, stages with different output
WW+BWS
121+129
WW+BWS
121+145
WW+BWS
129+145

Cooling water

If cooling water from an industrial waste heat process is used as heat
source for a water/water heat pump, observe the following:
VITOCAL 300-G
(cont.)
Plate heat Flow rate
exchanger Well circuit
(threaded)
Part no. m 3 /h
23.7 7248 338
31.4 7248 339
48.9 7199 407
47.4 7199 407
62.8 7199 409
97.8 7199 410
55.1 7199 408
72.6 7199 409
80.3 7199 410
Note
Fill primary circuit with anti-freeze mixture (brine, min. –5°C).
The operational reliability of a water/water heat pump improves when
it is used with a primary circuit heat exchanger. Subject to the correct
sizing of the primary pump and the optimum layout of the primary cir-
cuit, the coefficient of performance of the water/water heat pump will
be reduced by a maximum of 0.4.
We recommend the use of the threaded stainless steel plate heat
exchanger from the Viessmann Vitoset pricelist (manufacturer: Tranter
AG); see the following selection table.
Pressure drop
Primary circuit Well circuit
m 3 /h kPa
5.09 5.44
6.74 7.21
10.49 11.23
10.17 10.88
13.48 14.42
20.99 22.46
11.82 12.65
15.58 16.67
17.23 18.44
■ The water quality must be within the limit values (see "Basic princi-
ples", chapter "Heat recovery from groundwater", table "Resistance
of copper soldered or welded stainless steel plate heat exchangers
to substances contained in the water").
■ If the water quality falls outside these limits, use a stainless steel
heat exchanger in the primary circuit (see table on page 45). Sizing
is carried out by the manufacturer of the heat exchanger.
■ The available amount of water must satisfy the minimum flow rates
of the primary side of the heat pump (see specification).
■ The max. inlet temperature for water/water heat pumps is 25 °C.
With higher cooling water temperatures, low-end controllers (e.g. as
offered by Landis & Staefa GmbH, Siemens Building Technologies)
on the primary side of the heat pump must limit the max. inlet tem-
perature to 25 °C by adding cool return water.
Note
The utilisation of cooling water is also possible in conjunction with a
brine/water heat pump. The max. inlet temperature must
then be limited to 25 °C as for the water/water heat pump.
Primary circuit
3
kPa
20 25
25 30
20 30
20 30
20 30
20 30
20 30
20 30
20 30
VIESMANN
45