STIEBEL ELTRON HPG-I 04 S Premium - Evaporation Temperature; Condensing Temperature; Definition

Repair instructions
HPG-I 04-06-08-12-15 S-CS-DS-DCS
Premium
TQR
Page 46 from 48
D0000095883-c
21.1 Evaporation temperature
The manometric evaporation temperature (t0) essentially depends on the brine inlet temperature (toS1),
the superheat (Δtoh) and the power to be transferred in the evaporator. Simplified, it can be said that t0
= toS1 - Δtoh - x.
x is approximately the temperature difference between brine inlet temperature toS1 and evaporator outlet
temperature toh.
21.2 Condensing temperature
The condensing temperature tc is essentially dependent on the heating return temperature, the hot gas
temperature tvh and the power to be transferred in the condenser. At higher capacities, the condensing
temperature increases somewhat compared to low capacities. Due to the temperature glide of ~8K for
R454C in the wet steam region, the condensing temperature is dependent on the return temperature.
Therefore, a larger spread of 8K to 15K is advantageous, especially at high flow temperatures.
21.3 Overheating at the evaporator
In connection with the recuperator, the expansion valve is controlled in such a way that the refrigerant is
not yet completely superheated when it leaves the evaporator, especially at operating points with a high
pressure difference. In the recuperator, the refrigerant is re-evaporated and the minimum superheat of 2K
is ensured.
21.4 Definition
Naming
Unit of
measurement
Explanation
to
°C
Evaporation temperature (manometric)
toh
°C
Evaporation temperature (thermometric)
tc
°C
Condensing temperature (manometric)
tcu
°C
Condensing temperature (thermometric)
Δtoh
K
Overheating refrigerant vapour
Δtcu
K
Subcooling refrigerant
tVh
°C
Hot gas temperature
toS1
°C
Heat source temperature inlet
toS2
°C
Heat source temperature outlet