1.2m³ Refrigerated Air Dryer
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High Heat Exchange Efficiency & Energy Saving
Aluminum plate-fin exchangers reduce cooling load with up to 2°C air temp difference, saving energy. -
Compact with Large Heat Transfer Area
Multi-layer corrugated fins offer high efficiency in a space-saving design. -
Efficient Air-Water Separation
SST304 stainless steel mesh ensures high separation efficiency and durability. -
Enhanced Condenser Performance
Internally threaded copper tubes boost heat exchange by ~20%.
◆ Good heat exchange performance and saving energy consumption required for refrigeration . The heat exchange performance of aluminum plate-fin heat exchanger is much greater than that of conventional shell and tube heat exchanger. The maximum temperature difference between the inlet and outlet of air can reach 2 ℃, which reduces the required cooling capacity and thus saves energy consumption of the dryer.
| Heat exchanger series | Inlet and outlet temperature difference ℃ | Save energy |
| High-end small flow heat exchanger | 5-7 | 20% |
| Conventional tube-fin heat exchanger | 15~20 | High energy consumption |
| Large flow heat exchanger | 3-5 | 30% |
◆ Larger heat exchange area : Aluminum plate-fin heat exchangers are composed of multiple layers of corrugated fins and partitions. The fin spacing is very small and the number of layers is large, so the heat exchange area is large and the heat exchanger structure is compact ;
◆Stainless steel wire mesh filtration separation
The air-water separation of aluminum plate-fin heat exchangers is mostly done by stainless steel wire mesh filtration separation, which has the advantages of simple structure and high air-water separation efficiency. The stainless steel wire mesh is generally made of SST304 material, which is strong and corrosion-resistant.
◆ The condensers all use internally threaded copper tubes, which increase the heat exchange efficiency by about 20% compared to the bare tubes used by other brands;
◆High-end and efficient refrigeration accessories : Models with a processing flow rate ≥1 1 .5Nm³/min adopt a constant pressure expansion valve design , and the equipment is equipped with a defrost valve to ensure that the equipment will not have ice blockage in the compressed air path . It has strong reliability and uses Shanghai Shangheng /Denmark Danfoss/US Emerson hot gas bypass valves to ensure that there is no ice in the system.
♦ Good heat exchange performance, saving refrigeration energy consumption
The heat exchange performance of the aluminum plate-fin heat exchanger is much greater than that of the conventional shell-and-tube heat exchanger. The air inlet and outlet temperature difference can reach 2°C, reducing the required refrigeration capacity, thereby saving the energy consumption of the dryer.
| Heat exchanger series | Inlet and outlet temperature difference ℃ | Save energy |
| High-end small flow heat exchanger | 5~7 | 20% |
| Conventional tube-fin heat exchanger | 15~20 | High energy consumption |
| Large flow heat exchanger | 3~5 | 30% |
♦ Large heat exchange area
Aluminum plate-fin heat exchangers are made of multiple layers of corrugated fins and partitions. The fin spacing is very small and the number of layers is large, so the heat exchange area is large and the heat exchanger structure is compact.
♦ Stainless steel wire mesh filtration separation
The air-water separation of aluminum plate-fin heat exchangers is mostly done by stainless steel wire mesh filtration separation, which has the advantages of simple structure and high air-water separation efficiency. Stainless steel wire mesh is generally made of SST304 material, which is strong and corrosion-resistant.
♦ High-end and efficient refrigeration accessories
The models with a processing flow rate of ≤13.5Nm³/min use a constant pressure expansion valve design, and the models with a processing flow rate of ≥17m³/min use a capillary tube as a throttling device design, which has strong reliability, ensuring a continuous supply of refrigerant inside the evaporator, and a constant evaporation temperature of 2-3°. Shanghai Fengshen/Danfoss/Emerson hot gas bypass valves are used to ensure that there is no icing in the system.
♦ Automatic cooling water regulation
Danfoss WXF series water flow regulating valves are used to automatically adjust the cooling water injection amount according to the refrigerant pressure inside the dryer to ensure constant pressure stability of the system and stable compressor load
♦ Three-dimensional optimization design reduces welding points of refrigerant pipelines
As shown in the three-dimensional figure below, the refrigerant inlet and outlet evaporator interface has been replaced by a locking process instead of welding. After years of optimization design, the welding points of the refrigerant external circulation pipeline have been reduced to 5. Compared with the shell and tube refrigeration dryer, which has more than a dozen welding points, the probability of refrigerant leakage is extremely low.
| Model | Power (KW) | Capacity （M3/min） | Interface size | Dimensions (mm) | Weight (KG) | Refrigerant |
|---|---|---|---|---|---|---|
| SLT-1.2-1.6 | 7.5 | 1.2 | G¾'' | 500*450*700 | 40 | R134A |
| SLT-1.6-1.6 | 11 | 1.6 | G¾'' | 500*450*700 | 45 | R134A |
| SLT-2.6-1.6 | 15 | 2.6 | G1" | 500*460*750 | 50 | R410A |
| SLT-3.8-1.6 | 22 | 3.8 | G 1½'' | 600*500*775 | 65 | R410A |
| SLT-6.5-1.6 | 37 | 6.5 | G 1½'' | 600*560*860 | 70 | R410A |
| SLT-8.5-1.6 | 55 | 8.5 | G2" | 620*550*910 | 85 | R410A |
| SLT-11.5-1.6 | 75 | 11.5 | G2" | 1200*632*1206 | 160 | R410A |
| SLT-13.5-1.6 | 90 | 13.5 | G2" | 1200*632*1206 | 160 | R410A |
| SLT-18.5-1.6 | 110 | 18.5 | G2½'' | 1200*720*1310 | 180 | R410A |
| SLT-20.5-1.6 | 132 | 20.5 | G3" | 1200*720*1310 | 210 | R410A |
| SLT-25-1.6 | 150 | 25 | G3" | 1200*720*1310 | 230 | R410A |
| SLT-35-1.6 | 185 | 35 | G4" | 1400*1000*1575 | 320 | R410A |
| SLT-45-1.6 | 220 | 45 | DN100 | 1400*1000*1575 | 350 | R410A |
| SLT-55-1.6 | 280 | 55 | DN125 | 1485*1030*1945 | 550 | R410A |
| SLT-65-1.6 | 355 | 65 | DN125 | 1485*1030*1945 | 600 | R410A |
Technical analysis of refrigerated dryer: working principle, selection guide and performance optimization
In modern industrial production, compressed air, as the “fourth largest energy source”, is widely used in various production lines, automation equipment, instrumentation and other fields. However, compressed air will carry a lot of water and impurities during the compression process. If these water are not handled, it is very easy to cause rust of pneumatic equipment, pipeline blockage, product quality decline, and even cause safety accidents. Therefore, the drying and purification of compressed air has become a key link to ensure the smooth production.
As the mainstream equipment for compressed air dehumidification, refrigerated dryers have been widely used in food, pharmaceuticals, electronics, chemicals, machinery manufacturing and other industries due to their advantages of high efficiency, energy saving and easy maintenance. With the continuous development of industrial automation and intelligent manufacturing, users’ requirements for compressed air quality are increasing, and the technology of refrigerated dryers is also constantly innovating and upgrading.
This article will systematically analyze the working principle, selection points, and performance optimization methods of refrigerated dryers, and compare them with other drying technologies to help enterprises and technicians scientifically select and use them reasonably, and improve the overall efficiency and economy of compressed air systems.
Technical principle of refrigerated dryer
Detailed explanation of working mechanism
The core principle of refrigerated dryer is to use refrigeration cycle to cool compressed air to below dew point temperature, so that water vapor in the air condenses into liquid water, and then discharges the water through separator and automatic drainer to obtain dry compressed air. The detailed process is as follows:
- Precooling heat exchange: High-temperature and high-humidity compressed air first enters the precooler, and exchanges heat with the low-temperature dry air to be discharged, reducing part of the temperature, reducing the subsequent refrigeration burden, and improving energy efficiency.
- Deep cooling: The precooled air enters the evaporator and is further cooled to 2~10℃ under the action of refrigerant. At this time, a large amount of water vapor in the air condenses into water droplets.
- Gas-water separation: The cooled air passes through the high-efficiency gas-water separator, and the liquid water is effectively separated and discharged in time through the automatic drainer to prevent moisture residue.
- Reheating treatment: The low-temperature air after drying passes through the precooler again, exchanges heat with the newly entered high-temperature air, and returns to near room temperature to prevent condensation in the pipeline, while improving the overall energy efficiency of the system.
- Output dry air: Finally, the dry and temperature-appropriate compressed air is delivered to the gas point to meet the production process requirements.
Main components and their functions
Refrigeration compressor: Provides power for the refrigeration system, commonly available are piston type, screw type, vortex type, etc. The performance of the compressor directly affects the energy efficiency and stability of the dryer.
Evaporator: Realizes heat exchange between air and refrigerant, and is a key component for air cooling and water analysis. Efficient evaporator design helps improve dehumidification efficiency.
Condenser: Takes away the heat released by the refrigerant, commonly available are air-cooled and water-cooled. The heat dissipation capacity of the condenser affects the operating stability of the entire system.
Air-water separator: Used to efficiently separate condensed water to prevent moisture from entering downstream equipment with air. Equipment with high separation efficiency can significantly improve air dryness.
Automatic drainer: Timed or automatic discharge of separated condensed water to ensure continuous and efficient operation of the system and prevent secondary pollution caused by water accumulation.
Control system: Automatic monitoring and adjustment of parameters such as temperature, pressure, and drainage. High-end models also have functions such as remote monitoring, intelligent diagnosis, and data recording to facilitate operation and maintenance management.
Analysis of key technical parameters
Processing capacity (m³/min): refers to the volume of compressed air that the equipment can process per minute. When selecting, it is necessary to reasonably reserve margins based on actual gas consumption and future expansion needs.
Pressure dew point: indicates the lowest temperature after moisture in the air is removed. Refrigerated dryers can generally reach a pressure dew point of 2~10℃, which is suitable for most industrial applications. Some high-end models can achieve lower dew points.
Pressure loss: The resistance to air flow caused by the equipment when it is running. The smaller the pressure loss, the higher the system energy efficiency and the lighter the burden on the compressor.
Energy efficiency ratio (COP): a ratio of the energy consumption of the equipment to the dehumidification capacity. Equipment with a high energy efficiency ratio is more energy-efficient and has lower long-term operating costs.
Operation noise: affects the comfort of the working environment, especially in places with strict requirements on noise. Some brands use noise reduction design, which is quieter.
Refrigerant type: New environmentally friendly refrigerants (such as R134a, R410A, etc.) can not only improve refrigeration efficiency, but also reduce the impact on the environment.
Selection guide for refrigerated dryers
Key factors in selection
Matching of processing capacity and equipment
The processing capacity of the equipment should be slightly larger than the actual gas consumption to avoid the dehumidification effect being reduced or the equipment being started and stopped frequently due to excessive load. It is generally recommended to select 1.2~1.3 times the maximum gas consumption to cope with gas fluctuations and future expansion needs. Too small equipment will result in incomplete dehumidification, while too large equipment will increase investment and energy consumption.
Dew point temperature requirements
Different applications have different requirements for air dryness. For example, industries such as food and pharmaceuticals have high requirements for air cleanliness and dryness, and need to choose models with lower dew point temperature; while general industrial gas can choose equipment with conventional dew point. If the dew point requirement is extremely high, a refrigeration + adsorption combined drying solution can be considered.
Environmental conditions
The operating environment temperature, humidity, ventilation conditions, etc. of the equipment will affect its performance. In a high temperature and high humidity environment, the refrigeration load of the equipment increases, and a model with stronger refrigeration capacity needs to be selected. If the equipment is installed outdoors or in a high-temperature workshop, it is recommended to use products with protection and high temperature adaptability.
Energy efficiency and operating costs
Equipment with high energy efficiency not only saves energy and reduces consumption, but also reduces long-term operating costs. It is recommended to give priority to products with high energy efficiency ratio, variable frequency technology or new refrigerants. Some brands also provide energy consumption monitoring and energy-saving optimization functions to facilitate enterprises to manage energy consumption.
Maintenance and after-sales service
The convenience of equipment maintenance and the manufacturer’s after-sales service capabilities are also important considerations for selection. High-quality brands usually provide comprehensive technical support and spare parts supply to ensure long-term and stable operation of equipment. It is recommended to choose a manufacturer with local service outlets and rapid response capabilities.
Selection recommendations for different application scenarios
Food industry
Food processing has extremely high requirements for the cleanliness and dryness of compressed air. It is recommended to choose a refrigerated dryer with a high-efficiency filter and a low dew point to ensure that the air is oil-free, water-free, and impurity-free. Some food companies will also cooperate with multi-stage purification measures such as ultraviolet sterilization and activated carbon filtration.
Pharmaceutical industry
The pharmaceutical production environment has strict standards for air quality. It is necessary to use a high-performance, highly intelligent refrigerated dryer, and cooperate with an online monitoring system to monitor the air quality in real time. Some pharmaceutical companies will also use redundant configurations to ensure the continuity and safety of key process gas.
Electronic manufacturing
Electronic components are extremely sensitive to humidity. It is recommended to use a refrigerated dryer with a low dew point temperature and low pressure loss to prevent moisture from damaging the product. Some high-end electronics factories will also use a constant temperature and humidity control system to further improve air quality.
Chemical Industry
The chemical production environment is complex. It is necessary to select corrosion-resistant and easy-to-maintain refrigerated dryers according to specific process requirements, and pay attention to the explosion-proof and corrosion-resistant performance of the equipment. Some special processes also require customized special models to meet the needs of high temperature, high pressure or special gas processing.
Common Misunderstandings and Precautions in Selection
Only look at the price and not the performance: low-priced equipment often has shortcomings in energy efficiency, stability, after-sales service, etc., and the long-term operating cost is high.
Ignore environmental adaptability: Failure to select according to the actual ambient temperature and humidity leads to unstable equipment operation or poor dehumidification effect.
Ignore maintenance convenience: Some equipment has a complex structure and inconvenient maintenance, which can easily lead to operation interruption and increased maintenance costs.
Not considering future expansion: No margin was left when selecting, and the equipment could not meet the demand when the gas consumption increased in the later period.
Ignore supporting facilities: If suitable filters, gas storage tanks, etc. are not equipped, the operation effect of the overall system may be affected.
Refrigerated dryer performance optimization
Methods to improve energy efficiency
Optimize operating parameters
Reasonably set the inlet temperature, pressure and flow rate to avoid overloading or underloading the equipment. Regularly check and clean the heat exchanger and filter to keep the equipment running efficiently. Some intelligent control systems can automatically adjust the operating parameters according to the gas consumption to achieve on-demand gas supply.
Regular maintenance and cleaning
The evaporator, condenser, gas-water separator and other components of the refrigerated dryer need to be cleaned regularly to prevent dirt accumulation and affect the heat exchange efficiency. The automatic drainer should be kept unobstructed to prevent condensate accumulation. It is recommended to establish a regular maintenance plan to extend the service life of the equipment.
Use high-efficiency refrigerants and frequency conversion technology
New environmentally friendly refrigerants can not only improve refrigeration efficiency, but also reduce the impact on the environment. Frequency conversion technology can automatically adjust the compressor speed according to the actual load, significantly reducing energy consumption. Some high-end models are also equipped with energy consumption monitoring and energy-saving optimization functions to facilitate energy consumption management for enterprises.
Strengthen system integration and collaborative optimization
Integrate the refrigerated dryer with compressors, gas storage tanks, filters and other equipment, achieve collaborative optimization through intelligent control systems, and improve overall energy efficiency. Some companies will also use energy management systems to uniformly dispatch and optimize the gas and energy consumption of the entire plant.
Application of intelligent control
Remote monitoring and fault diagnosis
Modern refrigerated dryers are generally equipped with intelligent control systems, which can realize remote monitoring, data collection and fault warning. Through the Internet of Things platform, operation and maintenance personnel can grasp the operating status of the equipment in real time, discover and handle abnormalities in time, and reduce downtime losses.
Automatic adjustment technology
The intelligent control system can automatically adjust the operating parameters according to the changes in gas consumption, realize on-demand gas supply, and avoid energy waste. At the same time, functions such as automatic drainage and automatic defrosting improve the operating reliability and maintenance convenience of the equipment. Some high-end models also support self-learning and adaptive adjustment to further improve operating efficiency.
Energy-saving technology trends
Application of frequency conversion technology
Frequency conversion refrigerated dryers can dynamically adjust the compressor speed according to the actual load, significantly reduce energy consumption, extend equipment life, and are suitable for occasions with large fluctuations in gas consumption. Frequency conversion technology can also reduce the number of equipment starts and stops and reduce mechanical wear.
Promotion of new refrigerants
With increasingly stringent environmental regulations, refrigerated dryers using new refrigerants with low GWP (global warming potential) have gradually become mainstream, which can not only improve energy efficiency but also benefit environmental protection. Some brands are also developing fluorine-free refrigerants to further reduce environmental impact.
Heat recovery and waste heat utilization
Some high-end refrigerated dryers have heat recovery functions, which can use the heat released by the condenser for plant heating or process heating to further improve energy utilization. Heat recovery technology not only saves energy and reduces consumption, but also reduces the overall energy consumption cost of enterprises.
Comparison between refrigerated dryer and other drying technologies
Comparison between refrigerated dryer and adsorption dryer
Differences in working principles
Refrigerated dryer: condenses water by lowering the air temperature, suitable for most industrial occasions, and the dew point temperature is generally 2~10℃.
Adsorption dryer: uses adsorbents (such as activated alumina, molecular sieves) to adsorb moisture in the air, suitable for occasions with extremely high requirements for air dryness, and the dew point can reach -20℃, -40℃ or even -70℃.
Energy consumption and operating cost
Refrigerated dryers have low energy consumption, simple maintenance, and low operating costs; adsorption dryers require regular replacement or regeneration of adsorbents, and have high energy consumption and maintenance costs. The regeneration methods of adsorption dryers are divided into heatless regeneration and thermal regeneration. Heatless regeneration has low energy consumption but limited dew point, while thermal regeneration has high energy consumption but lower dew point.
Applicable scenarios
Refrigerated dryers are suitable for most industrial gas applications and are cost-effective; adsorption dryers are suitable for special industries that have extremely high requirements for air dryness, such as precision electronics, pharmaceuticals, laboratories, etc. Some companies will adopt a combined freezing + adsorption drying solution to balance energy efficiency and dryness.
Comparison between refrigerated dryers and membrane dryers
Membrane dryers separate water through selective permeable membranes and are suitable for small flow rates and occasions with low dryness requirements. Its advantages are simple structure and no need for electric drive, but limited processing capacity and high long-term operating costs. Membrane dryers are mostly used in small gas applications such as laboratories and medical treatments.
Advantages and limitations of refrigerated dryers
Advantages
Low energy consumption, economical operation
Simple maintenance, convenient operation
Wide application range, meeting most industrial needs
Mature technology, high reliability
Short investment return period, high cost performance
Limitations
Dew point temperature is limited, unable to meet extremely low dew point requirements
Sensitive to ambient temperature, performance degrades in high temperature environment
Some models are noisy, need to pay attention to selection
Sensitive to impurities such as oil mist and dust, need to be used with high-efficiency filters
Performance comparison of different brands/models
Mainstream refrigerated dryer brands on the market such as Atlas, Ingersoll Rand, Sullair, Hanbell, Fusheng, etc., each has its own characteristics. High-end brands have more advantages in energy efficiency, intelligence, after-sales service, etc., but the price is relatively high. Users can choose the appropriate brand and model according to actual needs and budget. It is recommended to refer to third-party test reports, user reputation and after-sales service capabilities to comprehensively evaluate the product cost performance.
Conclusion
As an indispensable key equipment in the compressed air system, the refrigerated dryer is widely used in various industrial fields due to its advantages of high efficiency, energy saving and easy maintenance. Correctly understanding its working principle, rationally selecting and focusing on performance optimization can not only effectively improve the quality of compressed air, but also reduce the operating costs of enterprises and improve production efficiency.
In the selection process, users should combine actual gas demand, environmental conditions, energy efficiency indicators and maintenance convenience to select a refrigerated dryer suitable for their own working conditions. At the same time, pay attention to the intelligentization of equipment and the application of energy-saving technology, actively adopt new refrigerants and frequency conversion technology to achieve green and low-carbon production.
In the face of increasingly fierce market competition and increasing environmental protection requirements, refrigerated dryer technology is also continuing to innovate. In the future, with the in-depth application of intelligent manufacturing and Internet of Things technology, refrigerated dryers will be more intelligent, efficient and environmentally friendly, providing more reliable and economical compressed air drying solutions for industrial production.
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