Hanbell RTM-090 - 3.5 Hot Gas Bypass (HGBP)

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19
Vol. 1.2 © 2020 Hanbell Precise Machinery Co., Ltd.
All rights reserved
Equation of safety margin line is a polynomial of IGV actuator’s opening in percentage.
While operating, beware the pressure difference exceed the safety margin.
z= a+b/x+cy+d/x
2
+ey
2
+fy/x+g/x
3
+hy
3
+iy
2
/x+jy/x
2
1. a、b、c、d、e、f、g、h、i、j are constant
2. z=Hz(minima operating frequency)；x= opening of IGV (%)/10；y= pressure ratio
Note：
1. When doing the minimum operation frequency calculation, 2~3Hz buffer will be considered.
2. Safety margin on each model is not the same, please contact HANBELL representatives.
3.5 Hot Gas By Pass (HGBP)
Hot gas bypass is to bypass gas refrigerant or liquid refrigerant from condenser into evaporator
through a proportional valve.
Function: When the load reaches certain value the surge would happen. To continue the low load
operation, the hot gas by pass valve can be opened to increase suction pressure and lower
discharge pressure as well as compression ratio.
Because hot gas bypass is to transfer compressed gas from the condenser (high-pressure side) to the
evaporator (low-pressure side), enormous noise may occur. It is recommended to enlarge the inner
diameter of piping after the HGBP valve to keep flow speed under 10 m/sec.
13500 rpm
13000 rpm
11700 rpm
10400 rpm
9100 rpm
7800 rpm
IGV 100%
I
GV
7
0%
I
GV
5
0%
I
GV
2
0%
13500 rpm operation
range at different IGV %
Operation range
IGV100% operation range
at different rpm
Pressure Ratio (Pr)
Cooling Capacity (kW)
Figure 3.6 Operating range