Products
Double effect hot water chiller
1.General Description
The double-effect hot water LiBr absorption chiller is an environmentally friendly central air-conditioning unit that utilizes medium-temperature hot water (typically above 85°C) as the driving heat source to produce chilled water (typically at 7°C). It excels at converting low-grade thermal energy (such as industrial waste heat, solar thermal collection, or district heating return water) into high-value cooling capacity, making it a key asset for cascading energy use and waste heat recovery.
2.Working Principle and Flow Diagram
2.1 Working principle
Liquid evaporation is a phase changing and heat absorption process. The lower pressure, the lower evaporation.
For example, under one atmosphere pressure, the evaporation temperature of water is 100°C, and at 0.00891 atmosphere pressure, the evaporation temperature of water will drop to 5°C. If a low-pressure environment can be established and water is used as the evaporation medium, low-temperature water with a saturation temperature corresponding to the current pressure can be obtained. If the liquid water can be continuously supplied, and the low pressure can be maintained stably, the low-temperature water of the required temperature can be continuously provided.
LiBr absorption chiller,depending on the characteristics of LiBr solution, takes the heat of steam, gas, hot water and other media as the driving source, and realizes the evaporation, absorption, condensation of refrigerant water and the generation process of solution in the vacuum equipment cycle, so that the low-temperature evaporation process of refrigerant water can continue. That means the function of continuously providing low temperature chilled water driven by the heat source can be realized.
2.2 Flow diagram
The working principle of a hot water chiller is illustrated in Fig. 1-1.
The refrigerant water from condenser absorbs the heat of chilled water and lower its temperature to setting value, then refrigerant water evaporates to vapor and enters absorber. The concentrated solution in absorber absorbs vapor, becomes diluted solution and releases absorption heat, which is taken away by cooling water to keep the absorption ability of solution. The diluted solution generated in absorber is delivered by solution pump to low temperature heat exchanger, where it is heated and then enters LTG. In LTG, the diluted solution is heated to boiling point by primary refrigerant vapor generated in HTG and generates the secondary refrigerant vapor. Meanwhile, the diluted solution is concentrated into intermediate solution and delivered by another solution pump. After heated by the high temperature heat exchanger, it enters HTG and heated to boiling point by hot water, then concentrated into a thick solution, and produces primary refrigerant vapor. The secondary refrigerant vapor produced in LTG and the primary refrigerant vapor are cooled by cooling water after entering condenser and condensed into refrigerant water. Through U-type pipe, it enters evaporator water plate, and the concentrated solution returns to the absorber to repeat the continuously cycling process as above. Cooling water is used to reduce the medium temperature in absorber and condenser. After being heated, it is connected to the cooling tower system and returned to the unit for circulation after cooling.
Fig. 1-1 Process Flow Diagram
2.3 Main Components and Functions
1. Generator
Generation Function: The generator is the power source of the chiller. The heat source enters the generator and heats the diluted LiBr solution. Water in the diluted solution evaporates in the form of refrigerant steam and enters the condenser. Meanwhile, the diluted solution concentrates into a concentrated solution.
Featuring a shell-and-tube structure, the generator comprises the heat transfer tube, tube sheet, support plate, shell, steam box, water chamber and baffle plate. As the highest-pressure vessel inside the heat pump system, the generator has an internal vacuum approximate to zero (a micro negative-pressure).
2. Condenser
Condenser Function: The condenser is a heat generation unit. refrigerant steam from the generator enters the condenser and heats the DHW to a higher temperature. Then the heating effect is achieved. After refrigerant steam heats the DHW, it condenses in the form of refrigerant steam and enters the evaporator.
Featuring a shell-and-tube structure, the condenser comprises the heat transfer tube, tube sheet, support plate, shell, water storage tank and water chamber. Normally, the condenser and the generator are interconnected directly by pipes, so they have basically the same pressure.
3. Evaporator
Evaporator Function: The evaporator is a waste heat recovery unit. Refrigerant water from the condenser evaporates from the surface of the heat transfer tube, taking away the heat of and cools down the CHW inside the tube. Thus waste heat is recovered. refrigerant steam evaporating from the surface of the heat transfer tube enters the absorber.
Featuring a shell-and-tube structure, the evaporator comprises the heat transfer tube, tube sheet, support plate, shell, baffle plate, drip tray, sprinkler and water chamber. The working pressure of the evaporator is around 1/10 of the generator pressure.
4. Absorber
Absorber Function: The absorber is a heat generation unit. Refrigerant steam from the evaporator enters the absorber, where it is absorbed by the concentrated solution. The concentrated solution turns into a diluted solution, which is pump delivered into the next cycle. While the refrigerant steam is being absorbed by the concentrated solution, huge quantities of heat absorbed are produced and heat the DHW to a higher temperature. Thus the heating effect is achieved.
Featuring a shell-and-tube structure, the absorber comprises the heat transfer tube, tube sheet, support plate, shell, purging pipe, sprayer and water chamber. The absorber is the lowest-pressure vessel inside the heat pump system and is under the greatest impact from non-condensable air.
5. Heat Exchanger
Heat Exchanger Function: The heat exchanger is a waste heat recovery unit used to recover the heat in the LiBr solution. Heat in the concentrated solution is transferred by the heat exchanger to the diluted solution for thermal efficiency improvement.
Featuring a plate structure, the heat exchanger has a high thermal efficiency and a notable energy saving effect.
6. Automatic Air Purge System
System Function: The air purge system is ready to pump out the non-condensable air in the heat pump and maintain a high vacuum condition. During operation, the diluted solution flows at a high rate to produce a local low pressure zone around the ejector nozzle. Thus the non-condensable air is pumped out of the heat pump. The system operates simultaneously with the heat pump. While the heat pump is working, the automatic system helps maintain a high vacuum inside and ensure system performance and a maximized service life.
The air purge system is a system composed of the ejector, cooler, oil trap, air cylinder and valve.
7. Solution Pump
The solution pump is used to deliver the LiBr solution and secure the normal flow of liquid working mediums inside the heat pump.
The solution pump is a wholly-enclosed, canned centrifugal pump featuring zero liquid leakage, low noise, high explosion-proof performance, minimal maintenance and a long service life.
8. Refrigerant Pump
The refrigerant pump is used to deliver refrigerant water and ensure the normal spray of refrigerant water on the evaporator.
The refrigerant pump is a wholly-enclosed, canned centrifugal pump featuring zero liquid leakage, low noise, high explosion-proof performance, minimal maintenance and a long service life.
9. Vacuum Pump
The vacuum pump is used for vacuum purging at the start-up stage and air purging at the operation stage.
The vacuum pump features a rotary vane wheel. The button to its performance is vacuum oil management. The prevention of oil emulsification has an obviously positive impact on air purging performance and helps lengthen the service life.
10. Electric Cabinet
As the control center of the LiBr heat pump, the electrical cabinet houses the main controls and electrical components.
Waste Heat Recovery. Energy Conservation&Emission Reduction
It can be applied to recover LT waste hot water or LP steam in thermal power generation, oil drilling, petrochemical field, steel engineering, chemical processing field, etc. It can utilize river water, groundwater or other natural water source, converting LT hot water into HT hot water for the purpose of district heating or process heating.
Intelligent Control&Easy Operation
Fully automatic control, it can realize one-button On/Off, load regulation, solution concentration limit control and remote monitoring.
Artificial Intelligent Control System AI (V5.0)
■Fully-automatic control functions
The control system (AI, V5.0) is featured by powerful and complete functions, such as one-key start up/shutdown, timing on/off, mature safety protection system, multiple automatic adjustment, system interlock, expert system, human machine dialogue(multi languages), building automation interfaces, etc.
■Complete unit abnormality self-diagnosis and protection function
The control system (AI, V5.0) features 34 abnormality self-diagnosis&protection functions. Automatic steps will be taken by system according to level of an abnormality. This is intended to prevent accidents, minimize human labor and ensures a sustained, safe and stable operation of chiller.
■Unique load adjustment function
The control system (AI, V5.0) has a unique load adjustment function, which enables automatic adjustment of chiller output according to actual load. This function not only helps to reduce startup/shutdown time and dilution time, but also contributes to less idle work and energy consumption.
■Unique solution circulation volume control technology
The control system (AI, V5.0) employs an innovative ternary control technology to adjust solution circulation volume. Traditionally, only parameters of generator liquid level are used to control of solution circulation volume. This new technology combines merits of concentration&temperature of concentrated solution and liquid level in generator. Meanwhile, an advanced frequency-variable control technology is applied to solution pump to enable unit to achieve an optimal circulated solution volume. This technology improves operating efficiency and reduces startup time and energy consumption.
■Solution concentration control technology
The control system (AI, V5.0) uses a unique concentration control technology to enable real-time monitoring/control of concentration and volume of concentrated solution as well as hot water volume. This system can maintain chiller under safe and stable at high-concentration condition, improve chiller operating efficiency and prevent crystallization.
■Intelligent automatic air purge function
The control system (AI, V5.0) can realize real-time monitoring of vacuum condition and purge out the non-condensable air automatically.
■Unique dilution stop control
This control system (AI, V5.0) can control operation time of different pumps required for dilution operation according to concentrated solution concentration, ambient temperature and remaining refrigerant water volume. Therefore, an optimal concentration can be maintained for the chiller after shutdown. Crystallization is precluded and chiller re-start time is shortened.
■Working parameter management system
Through interface of this control system (AI, V5.0), operator can perform any of following operations for 12 critical parameters relating to chiller performance: real-time display, correction, setting. Records can be kept for historical operation events.
■Unit fault management system
If any prompt of occasional fault is displayed on operation interface, this control system(AI, V5.0) can locate and detail fault, propose a solution or trouble shooting guidance. Classification and statistical analyses of historical faults can be conducted to facilitate maintenance service provided by operators.
