Energy Consumption Control of Coolant System
The application of coolant system has been very common.For example, pharmaceutical chemical industry, refrigeration, HVAC, heat pump and other systems.As the leading enterprise of domestic coolant carrier, glacier coolant has been supplied by more than 2000 enterprises, including new projects and transformation projects. The use effect has been highly praised, but the energy consumption in the use process is different. The owner often mentions the matter of energy consumption. Through our field investigation and analysis, we provide the owner with some opinions on energy conservation and emission reduction.
The first control point is mainly in the design stage. It is necessary to design a matching coolant system according to the physical properties of the refrigerant, so that the coolant pump, refrigeration compressor and end heat exchange can operate at the most efficient point. Such a system is the best for energy saving.This method is only suitable for new projects or projects with complete refrigeration system transformation.
The second control point is the selection of coolant. The design institute has little understanding of the physical properties of coolant. Generally, the physical parameters of ethylene glycol or brine are queried, and the parameters obtained are often insufficient, which will have a certain impact on the calculation.Finally, there will be high energy consumption in the process of operation.The energy consumption of the reconstruction project is generally high, so it is particularly important to select a suitable coolant, which can directly reduce the energy consumption. It is not an exaggeration to say that it is also possible to save 50% energy.
The third control point is the daily operation and maintenance. During the operation process, there are often gases entering the system. The filter or system impurities lead to the increase of system operation energy consumption, which requires regular maintenance.The physical parameters of the coolant need to be tested every year and adjusted in time to ensure the stable and efficient operation of the system.
The operation energy consumption of the coolant system is a whole process control, and each link needs to control the energy consumption.
Under the concept of carbon neutralization, the cooling system also needs fine control.This process requires a close combination of the design unit, the owner and the coolant manufacturer. As a coolant manufacturer, glacier coolant provides cooling system solutions to track the whole process of the project and realize energy conservation and emission reduction of the system.
Function of Intermediate Water Tank of Coolant System
There are many liquid supply forms of coolant system. According to the requirements of the system, primary pump liquid supply system and secondary pump liquid supply system can be set.At present, the secondary pump liquid supply system is widely used. The most important part of the secondary pump liquid supply system is the intermediate circulating water tank. The size of the water tank has a great impact on the stability of the system and the energy consumption of the system operation.Here is some analysis on the function of the intermediate water tank:
The circulation mode of the intermediate water tank: the primary water tank circulates with the refrigeration host, and the secondary water tank circulates with the end cooling equipment. Generally, the primary side is a constant flow system and the secondary side is a variable flow system.
The requirements of the primary side for the water tank mainly involve the start and stop of the host. The host generally has a short loading time and cannot be started again after shutdown. The interval is generally not less than 15 minutes. Therefore, it is necessary to ensure the load at the corresponding time after the host is shut down.
According to the requirements of the secondary side for the water tank, the end load of the secondary side is not a stable value. It is necessary to ensure that the cooling load of the water tank can provide the end load during the use process or during the reaction time when the main engine is shut down and loaded.In this case, the system can operate stably, and there will be no temperature oscillation in both the host and the end.
In addition, how to save energy in the intermediate water tank also needs to be considered.Assuming that the water tank is an infinite carrier, it can be understood as a cold source with constant temperature. The host transmits the cooling capacity during off peak power, and the end obtains the cold source from the water tank at any time according to the production needs.The operation energy consumption of this refrigeration system is about to reach the lowest, and the selection of equipment can also choose an efficient refrigeration host, which is the most ideal energy-saving practice. However, the actual capacity of the water tank needs to consider its economy and the investment and return in a reasonable range. At least its static payback period is within 5 years.
To sum up, the selection of intermediate water tank needs to fully consider the attributes of the system and select a reasonable intermediate water tank to ensure the operation of the whole system. Glacial coolant focuses on the systematic application of coolant.
Selection of End Pipe Arrangement Form of Coolant Cold Storage
Low temperature cold storage usually use exhaust pipes as heat exchangers, and the external heat transfer forms are natural convection and radiation heat transfer.In general, multiple circulation of refrigerant is used for liquid supply in the pipeline, which is mainly phase change heat exchange, with large local heat exchange. Generally, the cooling and temperature return are relatively fast.There will be a big difference when the heat exchange of exhaust pipe is used in the coolant system.The most intuitive feedback is that the temperature of the cold storage cannot be reached, or the cooling is relatively slow.In fact, it has a great relationship with the arrangement of system exhaust pipe, the pipe form of heat exchange exhaust pipe and the physical parameters of coolant.Glacier coolant through cold storage laboratory tests, different evaporator, different heat exchange pipe, different coolant, different pump circulation system found the following phenomenon.
Under the same heat exchange area, the cooling time of aluminum row tube is longer than that of smooth row tube, and the efficiency of aluminum row tube fin of load coolant system decreases obviously.
Under the same working condition and the same coolant, the cooling time of steel row pipe is close to that of aluminum row pipe. Considering the cost, the economic value of using ordinary seamless steel pipe is better.
The efficiency of the plate heat exchanger is significantly higher than that of the shell and tube heat exchanger. The channel in the shell and tube is several millimeters. The boundary layer of the coolant is relatively small, and the main thermal resistance of the heat exchanger is on the side of the coolant. The reduction of the measured thermal resistance of the coolant significantly improves the efficiency.
According to some comprehensive test data, during the transformation or design of the cold storage, the heat exchange exhaust pipe needs to be reasonably used. First, ensure the flow rate in the exhaust pipe, and then ensure that the cooling in the exhaust pipe is not too large or the single circuit is not too long.
The volume of coolant in the cold storage is small, and the finned tube is used. If it is really needed, the calculated heat exchange area needs to be increased by 30%.In addition, the pressure of the coolant system is generally 2 ~ 3bar. In fact, the pipe used can have less wall thickness and reduce the heat conduction and thermal resistance.
Glacier Coolant focuses on the coolant and provides various application system solutions.
Talking about the refrigeration mode of data center
The data center is part of the future infrastructure. There are more and more data centers in China. Due to the characteristics of high heat load of data center, energy saving of data center has become a hot topic.Especially in the case of carbon peak and double carbon targets, the cooling methods of data center are becoming more and more abundant.This paper mainly analyzes the refrigeration methods and practical conditions of several data centers.
The first is the traditional water-cooled or air-cooled chiller, which is used in most domestic data centers.With the optimization and improvement of the refrigeration system, PUE has reached below 1.4 from more than 2.0 at the beginning.However, due to the high condensation temperature in the south, the efficiency of the refrigeration host is low, so water-cooled units should be used in places with sufficient water resources.
The second is the use of natural cold source combined with traditional refrigeration system. This system is generally used in severe cold areas and cold areas in China.Referring to the application cases of some domestic data centers, the utilization of natural cold energy in such areas accounts for more than half of the time. Half of the extra investment recovery time shall not exceed 4 years, and some areas can recover it in one year.This natural energy recovery system is not standardized, and all data centers are exploring applications.Glacier coolant is specialized in making coolant. It has certain experience in cold energy recycling and can be combined with natural energy utilization in data center.
The third is fluorinated liquid immersion refrigeration, which has been tested in Alibaba data center. They use the boiling point of fluorinated liquid at 50 ℃, phase change refrigeration to cool the CPU, and then reflux through condensation and liquefaction. At present, the test effect is good.The advantage of this method is that the unit heat flux of fluorinated liquid phase change is large, which can meet the fan heat of high heat flux of CPU.In addition, some company use fluorinated liquid as cooling system, which circulates and cools the fluorinated liquid on the basis of immersion. Its heat transfer is between convection and subcooled boiling, and the heat transfer efficiency is also high. This scheme requires a large amount of fluorinated liquid, and the initial investment cost is high.
The fourth is evaporative refrigeration. This system mainly absorbs heat and refrigeration through the evaporation of water vapor without compressor compression. The power load of the system is low, and the PUE can reach 1.1.However, this scheme has a great impact on the weather, and the place with low wet bulb temperature is more appropriate, which is affected by geographical location. In addition, the refrigeration equipment has large volume and high investment.
The fifth is absorption refrigeration, which mainly uses waste heat for refrigeration, but the temperature of the heat source has a great impact on the refrigeration efficiency.The heat source recovered in the data center is at 50 ℃, the efficiency of absorption refrigeration is very low, and it is technically difficult.If there is a waste heat source with a temperature above 90 ℃, this method is still used for energy saving. This refrigeration scheme is rarely used at present. Most scientific research institutions are still exploring absorbing materials and reducing the temperature of recovered heat source.
The sixth is to use direct cooling system for refrigeration. At present, freon is being limited due to double carbon. The transcritical cycle or supercritical cycle of carbon dioxide can be utilized, which needs to be developed with the application of many scholars.
The forms of refrigeration methods are diverse, and the ultimate goal is energy conservation, environmental protection and stability, which is the goal of the data refrigeration system. Glacier coolant focuses on the application of data center and provides professional coolant.
Precautions for Transformation of calcium Chloride Brine Secondary Cooling System
Calcium chloride brine is widely used in practical engineering projects, and its advantages are prominent, such as high specific heat, high density, low viscosity, high thermal conductivity, low cost and so on. However, its disadvantage is also very prominent, that is, it is corrosive. The service life of each brine system will be relatively short. In addition, there will be many small problems within the service life, which requires a lot of manpower to maintain. Therefore, at present, high-end pharmaceutical enterprises no longer use brine and have adopted the corresponding products of glacier coolant.
The new project design institute is designed according to the physical parameters of glacier coolant, with good use effect and low operation cost. However, there are more or less minor defects in the use of the transformation project, and then summarize some precautions for the transformation of brine system:
- During the transformation of the refrigeration host, due to the different physical properties of the coolant, there should be a good trade-off between the cost and effect when selecting the coolant, and try to select the one with similar physical parameters to ensure the heat exchange.
- The transformation of the coolant pump is directly related to the effect of heat exchange. The change of coolant density and viscosity often leads to the cheap operation curve of the pump, which can not reach the design flow, resulting in slow cooling and unable to pull down the temperature. Therefore, in the transformation system, the pump needs to be rechecked and selected. Since the equipment cost of the pump is not high, it is recommended to replace the pump. Variable frequency pump is recommended for systems with long operation time and large load fluctuation.
- It is suggested to adopt the secondary pump circulation system and set a buffer pool in the middle. The larger the filling volume in the pool, the more stable the temperature during operation. However, considering the economy of initial investment, the end load and the frequency of start and stop of the main engine are comprehensively considered. Energy saving and stable operation of the system can be realized.
- For the cleaning of the original system, the calcium chloride in the system must be cleaned. Calcium chloride belongs to strong acid and weak alkali salt. The system is acidic and corrosive.
Glacial coolant has accumulated a lot of experience in the transformation of calcium chloride brine cooling system. The above are some common problems for your design reference, so as to avoid problems with changing the refrigerant directly.
Energy Consumption Control of Coolant System
The application of coolant system has been very common.For example, pharmaceutical chemical industry, refrigeration, HVAC, heat pump and other systems.As the leading enterprise of domestic coolant carrier, glacier coolant has been supplied by more than 2000 enterprises, including new projects and transformation projects. The use effect has been highly praised, but the energy consumption in the use process is different. The owner often mentions the matter of energy consumption. Through our field investigation and analysis, we provide the owner with some opinions on energy conservation and emission reduction.
The first control point is mainly in the design stage. It is necessary to design a matching coolant system according to the physical properties of the refrigerant, so that the coolant pump, refrigeration compressor and end heat exchange can operate at the most efficient point. Such a system is the best for energy saving.This method is only suitable for new projects or projects with complete refrigeration system transformation.
The second control point is the selection of coolant. The design institute has little understanding of the physical properties of coolant. Generally, the physical parameters of ethylene glycol or brine are queried, and the parameters obtained are often insufficient, which will have a certain impact on the calculation.Finally, there will be high energy consumption in the process of operation.The energy consumption of the reconstruction project is generally high, so it is particularly important to select a suitable coolant, which can directly reduce the energy consumption. It is not an exaggeration to say that it is also possible to save 50% energy.
The third control point is the daily operation and maintenance. During the operation process, there are often gases entering the system. The filter or system impurities lead to the increase of system operation energy consumption, which requires regular maintenance.The physical parameters of the coolant need to be tested every year and adjusted in time to ensure the stable and efficient operation of the system.
The operation energy consumption of the coolant system is a whole process control, and each link needs to control the energy consumption.
Under the concept of carbon neutralization, the cooling system also needs fine control.This process requires a close combination of the design unit, the owner and the coolant manufacturer. As a coolant manufacturer, glacier coolant provides cooling system solutions to track the whole process of the project and realize energy conservation and emission reduction of the system.
Application of Coolant in Hydrogenation Station
Hydrogen has a wide range of sources and no pollution of combustion products. It is expected to become one of the main energy carriers in the future.At present, hydrogen fuel cell vehicles have been commercialized, but a considerable number of hydrogenation stations are needed for further promotion.In 2020, China Society of automotive engineering issued the construction goal of China’s hydrogen refueling stations. From 2025 to 2030, the number of hydrogen refueling stations will increase from 1000 and 5000.By the end of 2020, 118 have been built in China, but hydrogen energy vehicles are still in its infancy.
At present, the hydrogenation station is mainly externally supplied, and the filling system generally consists of: hydrogen supply source, compressor, station side storage tank (high-pressure storage tank, medium pressure storage tank, etc.), pressure reducing valve, precooling and hydrogenation machine.Generally, the long tube trailer transports the hydrogen of about 20MPa to the hydrogenation station and pressurizes and fills it into the in-car automotive gas cylinder or high-pressure storage tank through the compressor. The compression process is generally a constant entropy process, which will increase the temperature of hydrogen. Under the rated pressure of limited space, the amount of stored hydrogen will be greatly reduced, so it must be cooled in the hydrogenation process.The cooling system will be one of the main costs of the operation cost of the later hydrogenation station. In Germany, the cooling cost of hydrogenation station exceeds 10kwh / kg H2. If the utilization rate of hydrogenation station is low, the cooling cost will be greatly increased.
In order to reduce the operation energy consumption of the cooling system, the carrier cooling system is generally used. The carrier cooling system can ensure the stability of hydrogenation process, reduce the starting frequency of refrigeration equipment and improve the cop of refrigeration system.
At present, the traditional coolant is mainly calcium chloride brine and ethylene glycol aqueous solution, but the service temperature of the hydrogenation station is low, which can generally be as low as – 40 ℃. The viscosity of ethylene glycol aqueous solution is too large to be used, and most choose calcium chloride aqueous solution.However, calcium chloride aqueous solution is particularly corrosive to the system. Generally, the equipment needs to be replaced in 3-5 years, which increases the fixed cost.At present, there are successful application cases of glacier coolant in hydrogenation station. It has high thermal conductivity, high specific heat, low viscosity and non corrosivity, and can be highly suitable for the cooling system of hydrogenation station.
Cooling Application of Coolant in Power Lithium Battery
Lithium battery is the power battery used in new energy vehicles at present. The power battery has high energy density and obvious heat generation during large rate charge and discharge, which is mainly caused by internal resistance and electrochemical polarization. The existing technology is mainly to cool it and ensure that the battery works at a stable temperature.
The best working temperature of lithium battery is 20~40℃. If the local temperature is higher than 80℃, it will run out of control and cause the battery to burn. Therefore, each power battery has its own set of heat pipe system.At present, there are many cooling methods studied, mainly including air cooling, liquid cooling, phase change material cooling and heat pipe cooling.
At present, the commercial lithium battery cooling technology is mainly air cooling and double circuit liquid cooling.Air cooling is forced convection heat transfer through natural wind. When the battery capacity increases, the heat dissipation effect is poor.Large capacity batteries are generally liquid cooled, which is mainly shared with the automobile air conditioning system. The coolant is cooled through the air conditioning system, and the coolant is circulated through the pump to cool the battery.This scheme is mainly concerned about the corrosivity of coolant and short circuit caused by liquid leakage.At present, glacier coolant LM-8 coolant has no corrosion and has corresponding applications in power batteries.
The cooling channel of power battery is characterized by large aspect ratio, and the width is generally less than 1mm, which belongs to the category of microchannel. The traditional automobile coolant is ethylene glycol solution, which has high viscosity and large thermal boundary layer, which is not conducive to microchannel heat exchange, and the temperature field in the battery is easy to be uneven, resulting in the decline of efficiency and life of the battery.LM-8 glacier coolant has large unit capacity and small viscosity change within – 40 ~ 40 ℃. It is especially suitable for the power battery of new energy vehicles used in the north. In the long-term low-temperature environment, it can ensure the circulation of coolant and the uniformity of flow field in the flow channel. Some dead corners can be recycled through injection, so that the temperature at each point during battery operation does not exceed the optimal temperature zone.Improve the efficiency and stability of the battery and provide favorable guarantee for the thermal management system of the battery.
Application of Coolant in Controlled Atmosphere Cold Storage
Controlled atmosphere cold storage is an advanced storage technology that combines the technologies of regulating low temperature and controlled atmosphere components.Controlled atmosphere components include:Nitrogen production equipment, ethylene removal equipment, carbon dioxide removal equipment, humidification equipment, gas analysis equipment, pressure balance bag, safety valve. Regulated low temperature includes: refrigeration host, circulating water pump, cooling fan, coolant, temperature control system. Different storage products require different temperatures and different indoor gas composition.
Nitrogen production equipment is mainly used to replace indoor oxygen, reduce the oxygen content in the controlled atmosphere cold storage to 5%, reduce the respiration of fruits and vegetables, effectively delay the aging of products, prevent diseases and bacteria, and inhibit the production of ethylene.Carbon dioxide removal is mainly to prevent high concentration of carbon dioxide, which will cause carbon dioxide poisoning. In general, the concentration of carbon dioxide must be controlled in the controlled atmosphere cold storage.Some fruits breathe actively, which will release plant hormone ethylene, leading to the maturity and aging of products. Therefore, the controlled atmosphere cold storage needs to be equipped with ethylene removal equipment.
controlled atmosphere cold storage has high requirements for the sealing of the storage body. At present, the assembled gas controlled storage is widely used, with fast cycle and good sealing performance. Generally, after completion, the atmospheric pressure test shall not be lower than 196pa, the half pressure drop shall be kept for 20 minutes, and the pressure shall not be lower than 78pa after the atmospheric pressure test. In order to reduce the impact of differential pressure caused by temperature change on he storage body, a pressure balance bag and a safety valve are set in the controlled atmosphere cold .
The refrigeration system of controlled atmosphere cold storage generally has direct cooling and indirect cooling. In terms of product storage quality, it is more appropriate to use coolant indirect refrigeration.The stable environment with small heat exchange temperature difference and high humidity provides better conditions for the preservation of products.
The coolant indirect cooling system has stable control and is suitable for the setting of storage conditions of different products.At present, the application proportion of controlled atmosphere cold storage in China’s high-temperature refrigeration system is still small, generally accounting for 5% ~ 7%.With the development of market demand, many unknown products still lack storage conditions, and more high-performance controlled atmosphere cold storage need to be put into use.In the future, the controlled atmosphere cold storage indirectly cooled by coolant will have a great market prospect. Glacier Coolant focuses on high-end controlled atmosphere cold storage system.
Application of Glacier Coolant in air separation system of LNG gasification station
At present, LNG cold energy utilization includes air separation, light hydrocarbon separation, power generation, refrigeration, etc., In air separation, the temperature region is close to each other, and the high-grade cold energy of LNG cooling can get high value.Air separation is mainly used to produce liquid oxygen, liquid nitrogen and liquid argon. Compared with the traditional air separation process, it saves 50% electricity, saves 90% water and has less carbon emissions.
Air separation system mainly includes filter compression system, air purification system, air separation distillation system, LNG heat exchanger cold box system, low-temperature liquid storage system, Coolant cooling system and nitrogen pipe network system. The interstage and final stage coolers of air compressors are cooled by Glacier Coolant as coolant.Air compressors and oil coolers use reheated Glacier Coolant to continue cooling.The heated Glacier Coolant is then cooled by centrifugation by pumping to a lower LNG heat exchanger to cycle cooling.
The cooling capacity of air separation unit is generally provided by liquid nitrogen.The high-pressure nitrogen is liquefied in the LNG-nitrogen heat exchanger, throttled to medium pressure and reduced liquid nitrogen temperature again , partially stored in the total pressure liquid nitrogen tank, partially throttled again and stored in the pressure liquid nitrogen tank. The pressure liquid nitrogen enters the liquid nitrogen separation heat exchanger, high-pressure nitrogen is liquefied, and the vaporized pressure nitrogen enters the low-temperature circulating nitrogen compressor to transfer the LNG cold energy to the air separation system.the heat exchange temperature of LNG-nitrogen heat exchanger is-120℃, divided into three pressure intervals, vaporized by different pressure, compression cycle.This process uses nitrogen as an inert gas,The heat transfer process is mainly nitrogen cycle, the system is more efficient and safe.
The pressurized low-temperature LNG is transported to the LNG-nitrogen heat exchanger through pipelines, part of it is directly vaporized to the NG pipe network, part of it is used to cool coolant, and also to the ng pipe network after vaporization.The utilization efficiency and technology of air separation system can be improved in theory.More technicians are needed to explore and improve LNG gasification air separation projects.
Glacier Coolant focuses on Coolantt, and will continue to focus on and study LNG gasification air separation system.