KIRLOSKAR KC Series User Manual

B) Compressor started at relatively low evaporation
temperature :
This situation occurs after the compressor has been
stopped for certain period of time because of low
capacity requirements of the installations.
UNDER SUCH CONDITIONS:
Start the compressor, observe evaporation
temperature. If it is less than t follow steps given in
1
5A or if temperature is less than t go to next capacity
2
steps and so on.
5.5 LIMITS OF OPERATIONS:
All capacity steps of compressor can be used for "PULL
DOWN TEMPERATURE" of system.
Once on 100% compressor load, the desired
temperature of product to cool, is attained, the
thermostat may cut off compressor capacity wise, as per
the system load is demanded for. For maintaining
minimum load requirements, compressor may shift to
minimum capacity requirement. For this minimum
capacity step you have to be very careful.
For determining minimum capacity control step :
Draw vertical line on "FIELD APPLICATION
DIAGRAM" (Fig. No 24) from design evaporation
temperature point and horizontal lines corresponding to
designed condensing temperature for every Ø value.
Note intersecting point of both these lines. For certain
value of Ø some points will be out of bounded area of
diagram. Capacity control steps corresponding to these
valves are not at all allowed for this application.
ALL THESE STEPS WILL BE WELL UNDER-
STOOD FROM EXAMPLE GIVEN BELOW
EXAMPLE NO.1:
Compressor KC 51 with Ammonia Gas, design
evaporation temperature -40°C and condensing
temperature 40°C. Saturation temperature on gauge
+30°C. (i.e. prolonged standstill condition of
compressors).
STEPS:
1. NOTE DOWN PARAMETERS OF REFRIGERA-
TION SYSTEMS:
A. Compressor Model KC 51
B. Gas Used in System Ammonia
C. Designed Condensing Saturation
Temperature of System = 40°C
D. Designed Evaporation Saturation
Temperature of System = -40°C
2. NOTE DOWN CAPACITY CONTROL STEPS
AND Ø VALUES FROM CAPACITY CONTROL
DIAGRAM (FIG. NO. 18) OF KC 51
COMPRESSOR.
CAPACITY STEP Ø VALUE
40% 2.0
60% 3.0
80% 4.0
100% 5.0
3. Draw horizontal line for 40°C condensing
temperature and Ammonia Gas for Ø = 2, 3, 4, 5.
Intersecting points, to right side of field application
bold lines, will be a1, a2, a3, a4. Corresponding to
these points read vertically down, to find minimum
evaporation temperature for every capacity step.
4. Point Evaporation Capacity Step
mini. Temperature
a1 t = - 12°C 40%
1
a2 t = - 22°C 60%
2
a3 t = - 27°C 80%
3
a4 t = - 32°C 100%
4
5. a. Start condenser water pump/Brine pump/
cooling tower fans pump etc.
b. Put all capacity control solenoid valve to OFF
position.
c. Start compressor. Observed evaporation
temperature is say 15°C. Run compressor on HP
Cylinder only till you get evaporation
temperature t =(-) 12°C.
1
d. Once you attain t = (-)12°C load compressor to 40%
1
capacity by operating solenoid valve 1 manually or
electrically. Let compressor run to 40% capacity till
evaporation temperature comes down to t = (-) 22°C.
2
e. Once you got evaporation temperature t = (-)22°C,
2
load compressor to next capacity step i.e. 60%
capacity. Run this compressor to this capacity till you
get next temperature t = (-)27°C.
3
f. Follow this sequence till compressor is loaded to
100%.
5.6 DETERMINATION OF LIMITS OF
OPERATION:
Determine minimum capacity control step to operate
compressor in two stages for taking care of reduced
installation heat load.
As described in limits of operating, draw a vertical line
on field application diagram corresponding to designed
evaporation temperature (-)40°C, and horizontal line
corresponding to designed condensing temp. 40°C for
Ø2, 3, 4, 5. Intersecting points will be points b1, b2, b3,
& b4 as shown. Since point b1 and b2 are falling outside
the bounded area, we cannot use capacity steps Ø2, and
3, i.e. capacity control steps 40% and 60% (Ø = 2 and 3)
cannot be used for maintaining designed evaporation
temp. -40°C. Minimum capacity steps to be used is 80%
(Ø = 4) only. (These 40% and 60% capacity steps can be
used for heat load pull down situation only.)
Since in this example, you are not permitted capacity
steps of 40% and 60% for taking care of minimum
external heat load, you may be tempted to run the
compressor on single stage i.e. (On HP Cylinders) all
solenoid valves are in off position. But do not do this.
Below 80% capacity operation, you stop running of
compressor till you get higher permitted evaporation
temperature for 60% loading of compressor.
20

KIRLOSKAR KC Series Specifications

General

Brand	KIRLOSKAR
Model	KC Series
Category	Air Compressor
Language	English