Hyundai HDFN-80-1400 User manual
HYUNDAI
CLIMATE CONTORL CO., LTD.
Operation Instructions
Gas/ Oil Direct-fired Absorption Chiller-heater
Models: HDFN-80 ~ 1400
2
FOREWORD
Thank you very much for your purchase of Hyundai Climate Control Co., Ltd. Gas/Oil Direct fired
Absorption Chillerheater
The absorption chillerheater manufactured under the rigid quality control system has excellent
performance, durability, and easy operation to meet your full expectation. Without a proper handling and
maintenance service of the absorption chillerheater, however, its excellent performance and durability
would not come to play. This manual gives information on the construction, functions of the principal
components and accessories, operation and maintenance required to operate and maintain the
refrigeration system correctly.
Please read this manual through carefully so that you can use Hyundai Climate Control Co., Ltd. Gas/Oil
Directfired Absorption Chillerheater under favorable conditions for a long period.
3
PRECAUTIONS
The following cautions shall be observed in order to ensure safe operations of the gas/oil direct-
fired absorption chillerheater.
1.Cautions before Starting Operation.
(1) Read this manual through before operating the absorption chillerheater. Especially, understand
the operating procedures of the important operations well prior to their actual operations.
(2) Do NOT use other fuels than designated in the nameplate of the absorption chillerheater. The
use of other fuel than designated may cause a fire.
(3) Do NOT use other power source than designated in the nameplate of the absorption
chillerheater. The use of other power source than designated may cause a fire or an electric
shock accident.
(4) Operate the absorption chillerheater under the designated design working pressure for
chilled/hot water and cooling water. The use of higher pressure than designated may cause
water leakage or burst to result in a short circuit or a burn.
(5) Do NOT put dangerous flammable liquid like gasoline, thinner, etc. and combustible materials
near the absorption chillerheater, smoke, duct, chimney and oil tank. They may cause a fire.
(6) Do NOT block the suction and discharge vents of the casing with obstructions, which may lead
to improper combustion to result in a fire or an oxygenpoor accident.
(7) Be sure to ventilate the air in the machine room sufficiently. If the air required for combustion is
in short, it may cause an oxygenpoor accident.
(8) Do NOT put heavy materials on the absorption chillerheater and the control panel.
It may cause injury, if they fall off.
(9) Check if the machine room smells of gas or if the fuel is not leaking or if the fuel feeding pipe is
correctly connected with the burner. When it smells of gas or the fuel leakage is observed, do
NOT operate the absorption chillerheater. Besides, do NOT operate the switches until the smell
of gas goes off. The operation while it still smells of gas or the fuel is still leaking may cause a
fire.
(10) Be sure to indicate on a label or a board that only expert engineers are allowed to operate the
chillerheater. If there is such a possibility as other persons than expert engineers reach the
absorption chillerheater, provide a protect fence around the chillerheater so that they can not
approach to the machine in order to eliminate any cause by which they may get injured.
2. Cautions During Operation
(1) Do NOT touch any parts of the absorption chillerheater except for the manual valves and the
control panel of which operation procedures are explained in this manual. If you perform
adjustment of the other parts than explained in this manual, it may cause a trouble of the
chillerheater or injury.
(2) Do NOT change the setting points set in advance at the factory for the safely advises and
protection devices. If the absorption chillerheater is operated set at wrong setting points, it may
cause a machine trouble or a fire.
4
(3) NEVER switch off the main power source during operation of the absorption chillerheater.
Besides, do NOT switch off even the machine is not operated except for a special case.
(4) Do NOT touch the switches in the control panel with wet hands. It may cause an electric shock.
(5) NEVER touch the combustion system. It may cause an oxygenpoor accident due to improper
combustion or a fire accident.
(6) Do NOT touch the electrical wiring in the control panel. It may cause an electric shock.
(7) Do NOT touch the high voltage wiring of the ignition transformer during operation. It may cause
an electric shock.
(8) Do NOT touch the absorption chillerheater as the control panel door is left open. It may cause
a trouble of the electrical instrument or an electric leakage.
(9) Do NOT insert fingers or a stick into the rotating parts of the fan and pump. It may cause injury.
(10) Do NOT touch the portions where a warming, “CAUTION: High Temperature” is labeled on the
absorption chillerheater. If you touch the portion, you may burnt.
(11) The high pressure generator, the low pressure generator, the high and the low temperature heat
exchangers, and the high temperature pipes have high temperature. Be careful not to touch
those parts so as not to get burnt.
(12) NEVER stop the operation of the chilled water pump until dilution operation of the chillerheater
is completed as per the operation sequence to eliminate a possibility of tube damages, etc.
NEVER stop the operation of the cooling water pump as well until it is completed as per the
operating sequence.
3. Cautions in Emergency
(1) If the vicinity of the absorption chillerheater should smell of gas or fuel leakage should be
observed while the machines is operating, stop the operation immediately and close the main
fuel supply valve. In such a case happens, contact our service agent to identify the portion of the
leakage and repair it as soon as possible.
(2) When airleak into the absorption chillerheater is detected, check first if the manual service
valve is fully closed. If airleak is still detected after the check, contact our service agent to
identify the portion of the leakage and repair it as soon as possible.
(3) If black smoke should generate from the chillerheater, stop the operation of the absorption
chillerheater to contact our service agent. If the chillerheater continues to operate. It may
cause a fire due to improper combustion.
(4) When there is any danger of a fire, an earthquake and falling of a thunder, stop the operation of
the absorption chillerheater right away. If you continue to operate the machine, it may case a
fire or an electric chock.
(5) When the safely devices or the protective devices actuate, remove the cause of their actuation
first and then restart the absorption chillerheater. If the machine is kept operating and repeats
start-stop operation without removing the cause, it may cause a fire.
5
4. Cautions for Changeover between Cooling and Heating, Inspection and Maintenance
(1) At the time of changeover between cooling and heating operation, be sure to understand the
operating procedure for changeover well and then changeover as per the procedure correctly.
(2) When the oil in the purge pump is replaced with new oil, be sure to stop the operation of the
pump to avoid injury and to splash of the oil.
(3) Be sure to perform a periodical inspection of the strainer, etc. and to remove the dusts and water
in the fuel pipe. If they remain in the piping, it may cause a fire due to improper combustion.
(4) Be sure to inspect the exhaust gas pipe periodically to confirm there is no gas leakage in order
to avoid an oxygenpoor accident.
(5) Be sure to switch off the power source of the absorption chillerheater when you clean or inspect
the cooing tower fan, the chilledhot water pump, etc. linked with the chillerheater to avoid an
electric shock or injury by the fan.
(6) Be sure to install or remove the heavy casing of the control panel carefully. If you handle it
carelessly, it may cause injury.
(7) Be sure to request our service agent for the inspection or maintenance lf the absorption
chillerheater. Improper inspection and maintenance may cause accidents such as an electric
shock, a fire or a burn.
(8) Be sure to use the fuses with correct capacity. Without using them, it may cause a machine
trouble or a fire.
(9) Do NOT let the absorption chillerheater and the control panel get wet. It may cause an electric
shock.
(10) Do NOT touch lithium bromide solution in stock or leaked lithium bromide solution directly with
hands. If lithium bromide solution is touched with metal or skin, it may cause metal corrosion and
skin inflammation by the deposition of the solution.
(11) Do NOT step on the absorption chillerheater. Falling off from the machine may lead to injury.
5. Cautions for Repairing, transferring or junking of the chillerheater.
(1) The structures of the absorption chillerheater and the electrical instruments in it are subject to
change without customer’s approval as far as customer’s requirements for specifications are
satisfied.
(2) No other persons than expert engineers shall disassemble, repair or modify the absorption
chillerheater. Imperfection in repairing, disassembling or modification may cause an electric
shock or a fire.
(3) The transfer and the movement of the absorption chillerheater shall be allowed only by expert
engineers. Imperfection in such works may cause a water leakage, an electric shock or a fire.
(4) When the absorption chillerheater is scrapped, request such a scrapping work to be done to
specialists. Imperfection in the work may cause the vessel to lead to metal corrosion or skin
inflammation by the deposition of the solution.
6
CONTENTS
CHAPTER 1 COMPONENT AND FUNCTION
1. Construction and Function of Major Components
1.1 Evaporator 9
1.2 Absorber 9
1.3 High Pressure Generator 9
1.4 Low Pressure Generator 9
1.5 Condenser 10
1.6 Solution Heat Exchangers 10
1.7 Purging System 10
1.8 Pumps 10
1.8.1 Solution pump, refrigerant pump 10
1.8.2 Purge pump (vacuum pump) 10
2. Cooling and Heating Cycle 14
2.1 Cooling Cycle 14
2.2 Heating Cycle 15
3. Capacity Control and Protective Devices 17
3.1 Chilled Water Temperature Control 17
3.2 Hot Water Temperature Control 17
3.3 Solution Flow Rate Control 18
3.4 Low Load Control 19
3.5 Emergency Stop 19
3.6 Protective Devices 19
CHAPTER 2 PREPARATION AND OPERATION
4. Preparation for Operation 24
4.1 Evacuation 24
4.2 Charging of Solution, Refrigerant andAlcohol 24
4.3 Checking of Rotation Direction of each Motor 26
5. Operation Procedure 27
5.1 Cautions During Initial Period of Operation 27
5.2 Preparation for Startup 28
5.3 Adjustment Procedure for Operation 29
5.3.1 Outline of solution flow 29
5.3.2 Adjustment procedure for solution flow rate 30
5.4 Cooling Operation 36
5.4.1 Starup 36
5.4.2 Stoppage 36
5.5 Heating Operation 38
5.5.1 Startup 38
5.5.2 Stoppage 39
5.6 Changeover between Cooling and Heating Cycle 39
7
5.6.1 Cooling to heating 39
5.6.2 Heating to cooling 40
5.7 Service Operation 40
6. Purging 40
6.1 Importance of Purging 40
6.2 Purging Operation 41
6.3 Vacuum Measurement 42
6.4 Continuous Purging 42
6.4.1 Explanation on the system of continuous purging 42
6.4.2 Operation procedure 43
7. Cautions During Operation 44
7.1 Checking of Solution Concentration 44
7.2 Decrystallization 44
7.3 Recording of Operation Data 45
8. Prolonged Shutdown 45
CHAPTER 3 MAINTENANCE AND INSPECTION
9. Maintenance and Inspection 45
9.1 Daily Inspection 46
9.1.1 Vacuum maintenance of the unit 46
9.1.2 Purging operation 46
9.1.3 Recording operation data 46
9.1.4 Others 46
9.2 Periodical Inspection 46
9.3 Maintenance of Purge Pump 47
9.4 Cooling Water Control 50
9.4.1 Temperature control 50
9.4.2 Water quality control for cooling water 50
9.4.3 Control of chilled/hot water and cooling water line
during prolonged shutdown 51
9.5 Inspection and Cleaning of Tubes 51
9.5.1 Mechanical cleaning 52
9.5.2 Chemical cleaning 52
9.5.3 Cautions for use 54
9.6 Solution Control 54
9.7 Combustion Control 54
10. Troubleshooting and Countermeasure 57
10.1 No Drop of Chilled Water Temperature in Cooling Operation 57
10.2 No Rise of Hot Water Temperature in Heating Operation 57
10.3 Improper Combustion 58
10.4 Actuation of Protective Devices 58
10.5 In Case of Power Failure 59
10.6 In Case of Emergency Like Earthquake and Fire 59
8
APPENDIX --- TECHNICAL INFORMATION AND DATA FOR REFRRENCE
1. Principle of Absorption Chillerheater 61
1.1 Vacuum 61
1.2 Principle of Absorption Chillerheater 61
1.2.1 Reason why heating can produce chilled water 61
1.2.2 Explanation on refrigeration cycle 62
1.2.3 Double effect (twostage) absorption chiller 64
2. Properties of Lithium Bromide Solution 64
2.1 General Properties 64
2.2 Solubility 65
2.3 Specific Gravity 65
2.4 Specific Heat 65
2.5 Vapor Pressure 65
2.6 PH 65
2.7 Corrosiveness 65
2.8 Others 65
3. Adjustment Procedure of Inhibiter for Lithium Bromide Solution 68
3.1 General 68
3.2 Standard of Lithium Bromide Solution 68
3.3 Sampling Procedure of Lithium Bromide Solution 68
3.4 Description on Container for Sampling 68
3.5 Charging Procedure of Chemicals 69
3.6 Subsequent Treatment 69
3.7 Caution for Handing the Chemicals 69
4. Spillover 69
9
CHAPTER 1 COMPONENT AND FUNCTION
1. Construction and Function of Major Components
Hyundai Climate Control Co., Ltd. Gas (oil) Directfired Absorption Chillerheater using pure water
as refrigerant, lithium bromide solution as absorbent, and gas (oil) as energy source.
The chillerheater consists of the main shell with low pressure generator, condenser, absorber and
evaporator, and the separate shell with high pressure generator, and solution pump, refrigeration
pump, solution heat exchangers, airpurging device, etc., and piping and control system.
The construction and function of these major components are explained as follow:
1.1 Evaporator
The evaporator sharing its shell commonly to the absorber contains the special tubes, pan,
eliminator, sprinkling baffle plate, spray nozzles, and other parts in itself, and is designed to
perform heat exchange between refrigerant and chilled water effectively.
Besides a sight glass is provided to check the refrigerant level. The refrigerant (pure water :
hereinafter referred to refrigerant ) pumped up from the refrigerant pump is sprayed over the
surface of the evaporator tubes, takes the heat from the chilled water running in the tubes, which is
used for air conditioning for buildings and for process cooling for factory, and is evaporated.
The pressure in the lower shell comprising the evaporator and absorber is about 6 mmHg abs.,
and the refrigerant evaporates at about 5 ℃. Therefore, when the chilled water enters the
evaporator at 12 ℃it is cooled down to 7 ℃.
1.2 Absorber
The concentrated solution (concentrated lithium bromide solution : hereinafter referred to
concentrated solution) which is returned from the low temperature heat exchanger is sprayed over
the surface of the absorber tubes and absorbs the refrigerant vapor from the evaporator
continuously to become dilute solution (dilute lithium bromide solution : hereinafter referred to
dilute solution) being collected at the bottom of the shell. The absorption heat generated here is
removed outside by the cooling water flowing in the absorber tubes.
1.3 High Pressure Generator
The high Pressure generator has a structure containing the furnace and heat transfer tubes in the
shell and equipped with the burner, which reflects the consideration of efficient and uniform heating
and anticorrosion. Asight glass to check the solution level and control system are provided with it.
The solution diluted by absorbing the refrigerant vapor in the absorber is sent to the low
temperature heat exchanger by the solution pump. About a half of the dilute solution flows into the
high pressure generator through the high temperature heat exchanger and it is heated by burning
gas flowing inside the furnace and on the surface of the tubes. Thus, a part of the refrigerant in the
solution evaporates and the dilute solution is concentrated. While, the burning gas is sent to the
smoke duct passing through the furnace.
1.4 Low Pressure Generator
The shell of the low pressure generator shares commonly to the condenser and tubes are high
efficient for heat transfer. The remaining dilute solution which is separated at the outlet of the low
temperature heat exchanger is sent to the low pressure generator and it is concentrated by the
refrigerant vapor generated in the high pressure generator. The concentrated solution sent from
the low pressure generator mixes with the intermediate concentrated solution returned from the
low pressure generator through the high temperature heat exchanger at the outlet box of the low
pressure generator and passes through the low temperature heat exchanger and is sprayed on the
upper part of the tubes in the absorber. In the low pressure generator is provided an over-flow pipe
with liquid-sealed structure so that the solution can flow into the absorber by the gravity and
differential pressure.
10
1.5 Condenser
The condenser is provided to condense, liquefy and cool down the refrigerant vapor generated in
the low pressure generator and the refrigerant drained in the tubes of the low pressure generator
by the cooling water flowing into the condenser tubes. The liquefied and cooled refrigerant is sent
to the upper part of the evaporator through the connection pipe by the gravity and differential
pressure and it is sprayed on the external surface of the evaporator tubes. An orifice is equipped
on the connection pipe to keep the differential pressure between the condenser and evaporator.
1.6 Solution Heat Exchangers
It consists of the low temperature heat exchanger and high temperature heat exchanger and it is
for increasing cycle efficiency to exchange the heat with the diluted and concentrated solution.
The solution diluted from the absorber is pumped up from the lower part of the absorber to be sent
partially to the high pressure generator through the high temperature heat exchanger. It is heated
in the low temperature heat exchanger by the high temperature concentrated solution coming from
the low pressure generator and is heated in the high temperature heat exchanger by the high
temperature intermediate solution coming from the pressure generator.
1.7 Purging System
The absorption chillerheater is designed to have an airtight structure to keep high vacuum.
However, hydrogen gas generates when the anti-corrosion thin film is formed in the vessel.
The purge system is provided to collect the hydrogen gas and noncondensable gas such as H₂
gas, air etc. and to purge out of the absorption chiller by the purge pump. The purge system
consists of the purge chamber, manual purge. The purge system consists of the purge chamber,
manual purge valve, absolute vacuum gauge, solenoid valve and purge pump. The proper purge
operation of the system (See CHAPTER 8) may prevent drop of refrigerating capacity and
corrosion in the machine or effect constant and stable operation of the chillerheater.
1.8 Pumps
1.8.1 Solution pump and refrigerant pump
The pumps used in the system are of canned type in which a motor is builtin. Because of this
there is no worry about leakage.
Solution pump #1
It sends the dilute solution from the absorber to the high pressure generator through the
solution heat exchanger.
Solution pump #2 (Applied 360RT and over)
It sends the concentrated solution from the low pressure generator to the absorber through
the solution heat exchanger.
Refrigerant pump
It absorbs the refrigerant coming from the lower part of the evaporator and sends the
refrigerant to atomizing main tube to spray it on the surface of the evaporator tubes.
1.8.2 Purge pump (Vacuum pump)
It is of gasballast type and is designed to purge the condensable gas containing some amount of
moisture. It sucks and purges out air and noncondensable gas entering the chillerheater through
the purge pipe and purge chamber.
11
Fig. 1.1 External View of Chiller-heater
12
Burner
High press.
generator
TE
4
SG
03
TE
3
LC
1
SG
02
SG
01
Service valve
(V-24)
OR-2
TE
1
63
EW
Dump valve
(V-16)
Chilled(hot)
water diffrential
press. switch
Chilled(hot)
water outlet
temp. sensor
Refrigerant
pump
Solution valve for
cooling/heating
(V-12)
Dilute sol. pump
Dilute Sol. flow rate
cont'l valve (TCV-2)
Service valve
(V-26)
Exhaust
gas outlet
Fuel inlet
Exhaust gas
temp. sensor
H.P generator
temp. sensor
High temp.
heat
exchanger
Low temp.
heat
exchanger
Absorber
Evaporator
Condenser
Low pressure
generator
Purge
Tank
OR-3
Cooling-heating
change over valve
(V-7)
Dilute sol. disribution
flow rate cont'l valve
(V-30)
Intermediate sol. flow
rate cont'l valve (V-29)
Service valve
(V-27) Dump valve
(V-14)
Dilute sol. flow rate
cont'l valve (V-31)
Service valve
(V-25)
Service valve
(V-28)
By-pass valve for
de-crystallization
(V-35)
By-pass valve for
de-crystallization
(V-41) Valve for purging
changeover
(V-42)
Sight
glass
Sight
glass
Sight glass
Valve for purging
(V-2)
Valve for purging
(V-3)
Valve for purging
(V-4)
Purge pump
Manometer
Chilled(hot)
water inlet
Chilled(hot)
water outlet
Cooling
water inlet
Cooling
water outlet
Service valve
(V-1)
Solenoid v/v
for purging
(SV-1)
High press. generator
flotless switch
63
GH
26
GH
PI
High press. generator
press. switch
High press. generator
temp. switch
Press gauge
Cooling
water pump
Chilled(hot)
water pump
TI PI
F
F
TI PI
TI PI
TI PI
Scope of work
by customer
Scope of work
by manufacturer
F
Scope of work by
manufacturer
Scope of work by
customer
Scope of
work by
customer
Scope of
work by
manufacturer
AIR VENT
AIR VENT
DRAIN
VALVE
DRAIN
VALVE
Cooling-heating
change over
valve (V-32)
MOV
(V-10)
(V-5)
HDFN-80∼310 FLOW SHEET
Solution cont'l valve
for heating(V-33)
13
Burner
High press.
generator
TE
4
SG
03
TE
3
LC
1
SG
02
SG
01
Service valve
(V-24)
TE
1
63
EW
Dump valve
(V-16)
Chilled(hot)
water differential
press. switch
Chilled(hot)
water outlet
temp. sensor
Refrigerant
pump
Solution valve for
cooling/heati ng
(V-12)
Solution
pump #1
Dilute sol. flow rate
cont'l valve (TCV-2)
Dervice valve
(V-26)
Exhaust
gas outlet
Fuel inlet
Exhaust gas
temp. sensor
H.P. geberator
temp. sensor
High temp.
heat exchanger
Low temp. heat
exchanger
Absorber
Evaporator
Condenser
Low pressure
generator
Purge
tank
OR-3
Cooling - heating change
over valve (V-7)
Dilute sol. distribution flow
rate cont'l valve (V-30)
Intermediate sol.
flow rate cont'l
valve (V-29)
Service valve
(V-27)
Dilute sol. flow rate
cont'l valve (V-31)
Service valve
(V-25)
Service valve
(V-28)
By-pass valve for
de-crystallization
(V-35)
By-pass valve for
de-crystallization
(V-41)
Sight
glass
Sight
glass
Sight
glass
Valve for purging
(V-2)
Valve for purging
(V-3)
Valve for purging
(V-4)
Purge pump
Manometer
Chilled(hot)
water inlet
Chilled(hot)
water outlet
Cooling
water inlet
Cooling
water outlet
Service valve
(V-1)
Solenoid valve
for purging
(SV-1)
H.P. generator
flotless switch
63
GH
26
GH
PI
H.P. generator
press. switch
H.P. generator
temp. switch
Press. gauge
Cooling
water pump
Chilled(hot)
water pump
TI PI
F
F
TI PI
TI PI
TI PI
Scope of work
by customer
Scope of work
by manufacturer
F
Scope of work by
manufacturer
Scope of work by
customer
Scope of
work by
customer
Scope of
work by
manufacturer
AIR VENT
AIR VENT
DRAIN
VALVE
DRAIN
VALVE
Refrigerant
distribution flow rate
cont'l valve (V-18)
L.P generator
by-pass solenoid
valve (SV-4)
Solution
pump #2
Concentrated sol. flow
rate cont'l valve (V-34)
Dump
valve (V-14)
MOV
MOV
LC
3
(V-6)
(V-5)
(V-10)
(V-36)
HDFN-360∼1400 FLOW SHEET
Purging change
over valve (V-42)
Concentrated sol. flow
rate cont'l valve (TCV-3)
14
2.Cooling and Heating Cycle
Both cooling and heating operation is available with a single unit of the chillerheater only by
switchingover. The absorption cycle in each operation mode is explained respectively as follows :
2.1 Cooling Cycle (See Fig.2.1A)
The main shell is divided into two parts, lower shell and upper shell. Since containing the absorber
and evaporator is maintained at a high degree of vacuum of about 6 mmHg abs., the refrigerant
sprayed over the surface of the evaporator tubes boils at the saturation temperature corresponding
to this pressure and is evaporated by taking heat from the chilled water flowing in the evaporator
tubes.
In order to effect the heat exchange, the refrigerant is sprayed on the evaporator tubes by the
refrigerant pump with the special nozzles. The lithium bromide solution in the absorber absorbs the
evaporated refrigerant to be diluted about 59% concentration. The absorption heat generated is
taken out by the cooling water. The solution diluted by absorbing the refrigerant in the absorber is
sent to the low temperature heat exchanger and is carried partially to the low pressure generator
and the rest to the high pressure generator through the high temperature heat exchanger by the
solution pump. The solution in the high pressure generator is heated and boiled by the burning gas
(oil) flowing around the surface of the generator tubes to make the refrigerant in the solution be
evaporated. The evaporated refrigerant flows into the low pressure generator tubes and heats the
solution around the tubes. And the refrigerant vapor condenses and flows into the condenser to be
cooled by the cooling water flowing in the condenser tubes.
As the upper shell containing the condenser and low pressure generator is kept at a high vacuum
of about 60 mmHg abs., the condensed refrigerant is sent to the evaporator by differential pressure
between the upper shell and lower shell and gravity to be sprayed in the evaporator.
While, the diluted solution which is diverged from the outlet of the low temperature heat exchanger
is sprayed on the surface of the low pressure generator tubes and heated to be concentrated. And
the intermediate concentrated solution which is heated and concentrated in the high pressure
generator enters the outlet box of the low pressure generator through the high temperature heat
exchanger and then it is mixed with the concentrated solution and sent to the absorber through the
low temperature heat exchanger to absorb the refrigerant vapor. Thus, one cycle of water and
lithium bromide solution completes.
Further, Fig. 2.2 shows the cooing cycle of the absorption chillerheater on the lithium bromide
solution P.T.X. chart. The following is an explanation on Fig.2.2
Point a :A state of the absorber
Point a~b : A state where the dilute solution going out from the absorber is heated in the
low temperature heat exchanger.
Point b~c : A state where the dilute solution is heated further in the high temperature heat
exchanger.
Point c, d~e : A state where the dilute solution heated in the high pressure generator is
concentrated to be intermediate concentrated solution.
Point e~f : A state where the intermediate concentrated solution going out from the high
pressure generator is cooled down in the high temperature heat exchanger.
Point b~g : A state where the dilute solution entering the low pressure generator is heated
and concentrated to be concentrated solution.
Point f~g : A state where intermediate concentrated solution going out from the high
temperature heat exchanger enters the outlet box of the low pressure
15
generator and is mixed with the concentrated solution from the low pressure
generator.
Point g~h : A state where the concentrated solution going out from the low pressure
generator is cooled down in the low temperature heat exchanger.
Point h~I : A state where the concentrated solution is sprayed on the surface of the
absorber tubes to be cooled down in the low temperature heat exchanger.
Point i~a : A state where the concentrated solution absorbs the refrigerant to be diluted in
the absorber.
2.2 Heating Cycle (See Fig.2.1 B)
The refrigerant vapor going out from the high pressure generator is sent to the evaporator and
heats the hot water up to the required high temperature. The circulation of the solution applies
correspondingly to the cooling cycle mentioned above.
16
17
3. Capacity Control and Safety Devices
3.1 Chilled Water Temperature Control
The signal sent from the temperature sensor installed at the water head of the chilled water outlet
controls the fuel consumption of the high pressure generator to ensure an efficient operation even
to part load.
Chilled water outlet temperature
Temperature Controller
Fuel control valve
(Compare to the set point) Valve action(Fuel control)
Rise-up Open
Chilled water Balanced Stop
outlet temperature Go-down Close
3.2 Hot Water Temperature Control
The signal sent from the temperature sensor installed at the water head of the hot water outlet
controls the fuel consumption of the high pressure generator.
(Compare to the set point) Valve action(Fuel control)
Rise-up Open
Hot water Balanced Stop
outlet temperature Go-down Close
TE-1
TE-1
Fuel control valve
Fig.3.1 Chilled/Hot Water Temperature Control System Chart
Chilled water temperature controller
DM
18
3.3 Solution Flow Rate Control
The reduction of the solution flow rate by the speed control of solution pump ensures an efficient
and stable operation in cooling operation at partial load.
Since the pressure of the high pressure generator reduces due to the reduction of the fuel
consumption in partial load, the solution level in the high pressure generator tends to rise up.
Detecting the solution level with the electrode, the speed of solution pump is controlled to keep the
correct level.
Level too high Solution pump stop
Level high Speed of solution pump Ⅰdecrease
Solution level in high Proper level Speed of solution pump Ⅰunchanged
Pressure generator Level low Speed of solution pump ⅠIncrease
Level too low Combustion stop
(Prevention of void combustion)
Inside control panel
Electrode column
In high pressure generator
inside
inverter
Motor revolution
Control Main gas valve
Solution pump
Fig.3.2 Solution Flow Rate Control System Chart
LC-01
(Level controller)
DM
INV1
(Inverter)
M1
19
3.4 Low Load Control
Chilled water temperature, hot water temperature and solution flow rate are controlled by the way
mentioned above and the chillerheater keeps on efficient and stable operation from full load to low
load. When the load of chilled water or that of hot water goes down under the set point, the gas
control valve closes to stop the operation of the chillerheater. This action is called “Low load stop”.
This action is made by the thermostat installed at the outlet of chilled water or hot water. Further,
when the chilled water or hot water temperature reaches the operating range, the chillerheater will
begin to operate automatically again.
Fig.3.3 Low Load Stop Flow Diagram (Cooling)
Fig.3.4 Low Load Stop Flow Diagram (Heating)
3.5 Emergency Stop
When the chiller-heater falls in any unfavorable condition for operation due to external cause, the
main gas valve closes automatically to stop operation of the chiller-heater. Refer to the Table 3.1
List of Protective Devices for detail stop of operation.
3.6 Protective Devices
When the chiller-heater is detected to be abnormal in pressure, temperature, etc., the machine is
forced to stop the operation of the functional parts such as pumps, a fuel control valve and so on
and to actuate protective devices. Besides, when crystallization begins temporarily, the de-
crystallizing system actuates automatically to prevent from crystallization.
The actuating conditions and safety action of the protective devices are shown in the Table 3.1
Chilled water
thermostat
OFF
Dilute operation
(approx, 20
minutes)
Solution
Pump
STOP
Damper low
combustion
position
High pressure generator
Solution temp. below rated
value
Refrigerant
Pump
STOP
Hot water
Thermostat
OFF
High pressure generator
Solution temp. below rated
value
Refrigerant
Pump
STOP
Dilute operation
(approx, 20
minutes)
Solution
Pump
STOP
Main gas
Valve
CLOSE
20
Fig. 3.5 Operation Flow Chart
Table of contents
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