Lithium bromide refrigerator working principle, advantages and disadvantages and maintenance methods
The lithium bromide refrigerator uses lithium bromide aqueous solution as the working medium, wherein water is the refrigerant and lithium bromide is the absorbent. Lithium bromide is a salt, white crystal, soluble in water and alcohol, non-toxic, chemically stable, and will not deteriorate. Lithium bromide aqueous solution has strong corrosiveness to steel in the presence of air. The following editor will introduce the working principle, advantages and disadvantages and maintenance methods of lithium bromide refrigerators. I hope it will be useful to everyone!
First, the working principle of lithium bromide refrigerator
Lithium bromide refrigerators use the absorption and release of water vapor from lithium bromide aqueous solutions at different temperatures to achieve refrigeration. This cycle uses external heat sources to achieve refrigeration, and commonly used heat sources are steam, hot water, gas, fuel oil, etc. Because lithium bromide refrigerators have many unique advantages, they have developed rapidly in recent years, especially in air conditioning and refrigeration. So whether the application of lithium bromide refrigerator is conducive to improving the utilization rate of primary energy, whether it saves energy, under what circumstances can save energy, and whether to use absorption refrigerators for cold and heat sources has always been the focus of debate. The practical application of lithium bromide refrigerator and its service life are directly related to the economic benefits of practical projects.
Lithium bromide uses heat energy as power source, water as refrigerant, and lithium bromide solution as absorbent to prepare cold source water, which is called lithium bromide refrigerator. The heat sources mainly include steam, hot water, gas and fuel oil, etc., which can be divided into direct combustion type, steam type and hot water type. Steam-type units are mainly used in occasions where steam can be used, such as urban central heating and heating networks, combined heat, power and cooling systems, textile, chemical, metallurgical and other industries; hot water-type units can use hot water above 65 degree , such as Geothermal, solar thermal energy, waste heat and hot water produced by industrial processes to produce cold water. Direct-fired units can use gas to provide air conditioning for large buildings such as hotels, hospitals, office buildings, and airports. Because it uses heat to cool, the lithium bromide refrigerator can also use industrial waste heat to provide cold water or air conditioning for the industry.
Lithium bromide refrigerators are unique in the field of central air conditioners because of their low-grade heat energy, low required electrical power, water as refrigerant, and no damage to the environment by lithium bromide solution. Encouraged by the government and the power sector. Since the late 1980s, there have been more than 100 lithium bromide air conditioner manufacturers in my country, and the manufacturing level and output of their products are second only to Japan and are in the forefront of the world.
Second, the advantages of lithium bromide refrigerator
1. Powered by thermal energy, it does not need to consume a lot of electricity, and the requirements for thermal energy are not high. It can utilize all kinds of low-potential heat energy, waste gas and waste heat, such as saturated steam higher than 20kPa (0.2kgf/cm2) (gauge pressure), various exhaust gas; hot water higher than 75 degree , geothermal heat, solar energy, etc., which are beneficial to the heat source comprehensive utilization, so the operating cost is low. If all kinds of waste gas and waste heat are used for refrigeration, a large number of cold sources can be obtained without running costs, which has good power saving and energy saving effects, and is highly economical.
2. The entire refrigeration unit has no other moving parts except the canned pump with low power. It has low vibration, low noise and quiet operation. It is especially suitable for hospitals, hotels, canteens, office buildings, theaters and other occasions.
3. Using lithium bromide solution as the working medium, the refrigerator operates in a vacuum state, which is odorless, non-toxic, non-explosive, safe and reliable. It is known as a pollution-free refrigeration equipment, which is beneficial to meet the requirements of environmental protection.
4. Wide cooling capacity adjustment range. With the change of external load, the unit can perform stepless adjustment of cooling capacity within the range of 10 percent to 100 percent , and when the low load is adjusted, the thermal efficiency hardly decreases, the performance is stable, and it can well adapt to the requirements of variable loads.
5. Strong adaptability to changes in external conditions. For example, the standard external conditions are steam pressure of 5.88XlOSpa (6kgf/cm2) (gauge pressure), the inlet temperature of cooling water is 32 degree , and the outlet temperature of refrigerant water is 10 degree . ) XlOSPa (2.0-8.0kgf/emz) (gauge pressure), cooling water inlet temperature 25-40 degree . Stable operation in a wide range of refrigerant water outlet temperature 5-15 degree .
6. The installation is simple and the requirements for the installation foundation are low. Due to the minimal vibration during operation, no special stand is required. Can be installed indoors, outdoors, ground floor, floor or roof. During installation, only general leveling is required, and the gas, water pipes and power supply can be connected.
7. Simple to manufacture, easy to operate and maintain. Except for auxiliary equipment such as canned pump, vacuum pump and vacuum valve, the unit is almost all heat exchange equipment, which is relatively easy to manufacture. Due to the stable performance of the unit and strong adaptability to changes in external conditions, the operation is relatively simple. The maintenance work of the unit is mainly to maintain the required air tightness.
3. Disadvantages of Lithium Bromide Refrigerator
1. In the presence of air, lithium bromide solution is highly corrosive to ordinary carbon steel. This not only affects the life of the unit, but also affects the performance and normal operation of the unit.
2. The refrigerator operates under vacuum, and the air is easy to leak. Practice has proved that even a small amount of air leakage will seriously damage the performance of the unit. For this reason, the refrigerator requires strict sealing, which adds difficulty to the manufacture and use of the unit.
3. Due to the direct utilization of heat energy, the heat exhaust load of the unit is relatively large, because the condensation and absorption process of the refrigerant vapor all need to be cooled. In addition, the water quality requirements for cooling water are relatively high. In places with poor water quality, special water quality treatment should be carried out during use, otherwise the normal performance of the unit will be affected.
Third, the maintenance method of lithium bromide refrigerator
In order to make the lithium bromide absorption refrigeration unit operate more stably and restore its cooling effect as much as possible, daily maintenance is very important. Under normal circumstances, in order to make the lithium bromide absorption refrigeration unit operate better and more stably and restore its cooling effect as much as possible after each unit runs for 3 years, daily maintenance is very important. Under normal circumstances, each unit needs to be maintained for about 3 years in operation, such as heat transfer tube cleaning and lithium bromide solution regeneration. Otherwise, it will increase energy consumption and reduce its cooling capacity, and at the same time affect the service life of the unit. Maintenance such as heat transfer tube cleaning and lithium bromide solution regeneration is required, otherwise it will increase energy consumption and reduce its cooling capacity, and at the same time affect the service life of the unit.
1 Lithium bromide solution regeneration treatment
During the operation of the equipment, the chemical composition of the lithium bromide solution will change to a certain extent with the increase of the running time, mainly the qualitative change of the lithium bromide solution at high temperature and the corrosion of the iron plate. Therefore, the lithium bromide solution needs to be regenerated after running for a certain period of time, which plays a key role in the service life of the equipment. At the same time, the addition of octanol in the lithium bromide solution plays a positive role in stabilizing the cooling effect of the equipment.
2 Cleaning of heat transfer tubes
During the operation of the equipment, the cooling water system through which the absorber and condenser pass through is an open system, so impurities such as sand and ash layer are often brought in. The tap water or deep well water used at the same time contains certain scaling components; After time, the equipment is easily scaled or the copper pipes are blocked, which will affect its heat exchange and affect the cooling effect. Evaporators are generally closed. According to past experience, the system is prone to sludge adsorption, and the exchange effect is also relatively poor. Therefore, after a period of operation, the equipment needs to be cleaned. Open the sealing plate and clean it manually;
3 Replacement and tightness inspection of wearing parts of the unit
The valves used in lithium bromide refrigerator equipment are generally diaphragm valves. The rubber products used for the valve plates are easy to age, so they should be replaced after a period of use; the sight glass will also be partially corroded, which is very inconvenient to observe. It is recommended to replace it.
4 Equipment control, verification of alarm system
The equipment alarm system plays a major role in protecting its operation, so all alarm systems should be normal, and regular inspection and verification play an important role. Check the status of the contactors and thermal relays in the control cabinet, and replace them if necessary.
