Refrigeration Unit Research Articles

Performance of refrigeration unit using monitoring of temperature, humidity and power consumption of freezer machine at Jaya Bahari cold storage

Fishery products generally spoil more quickly than other animal meat products. After being caught, fish will experience changes in quality, the level of these changes will determine the shelf life of the fish. Handling fresh fish is the most important aspect of a fisheries business. Cold storage is a way of storing fish at a certain temperature which allows fresh fish to be stored for long periods, even months, to prevent bacterial growth. This research aims to evaluate the implementation of the Standard Operating Procedure (SOP) for storing fish in cold storage using the First In First Out (FIFO) system and to evaluate the quality of the cooling system using temperature and humidity monitoring at Jaya Bahari cold storage. The method used in this research is measurement, interviews and literature study. The process stages in receiving fish products start from unloading fish, thawing frozen fish, weighing and testing samples, sorting and calculating the percentage of rejects, as well as temporary storage by looking at various obstacles during the process of receiving raw materials. The performance of the data logger and big data each showed results that were not much different with the respective tool accuracy values of 99.26% for temperature measurements and 99.83% for humidity measurements. Defrosting ice for 2 hours can save power by 4.37%.

Gas turbine-based system taking advantage of LNG regasification process for multigeneration purposes; Techno-economic-environmental analysis and machine learning optimization

It is viable for engineers to determine how thermodynamic systems can benefit from heat recovery in order to improve efficiency, reduce costs, and lower carbon dioxide emissions. The authors of the study propose a new energy system that incorporates various cycles and units, including gas turbines, Rankine and two organic Rankine cycles, an absorption refrigeration unit, a proton exchange membrane (PEM) electrolyzer, and a liquefied natural gas (LNG) unit. The hydrogen produced is stored and transferred for use as fuel. The system was modeled and optimized using MATLAB programming software, with a parametric study and sensitivity analysis conducted before employing a genetic algorithm optimization to find the most suitable performance conditions. Modifying the compressor's pressure ratio within the range of 6–18 caused a shift in the cooling load, ranging from 45 to 36 MW. Nonetheless, these adjustments in pressure ratio yielded a reduction of 0.4 Cent/kWh in levelized cost of electricity (LCOE) and 0.15 $/kg in levelized cost of hydrogen (LCOH). In the base design mode, the total cost rate is 5715.3 $/h, the exergy efficiency is 39.03%, and the normalized CO2 emissions are 335.89 kg/GJ. However, the optimization results showed a reduced total cost rate of 1884.50 $/h, along with an improved exergy efficiency from 39.03% to 40.32% and a decrease in annual CO2 emissions from 211,000 metric tons to 175,000 metric tons. The implementation of artificial neural networks (ANN) has significantly decreased the time required for optimization from 47 h to just 16 min.

Experimental study on a -86°C cascade refrigeration unit with environmental-friendly refrigerants R290-R170.

Ultralow-temperature refrigeration faces significant issues linked to the security of the cold chain for the production, storage, transportation, and distribution of COVID-19 vaccines. The use of environmentally friendly refrigerants in cascade refrigeration systems (CRS) to provide low-temperature range is motivated by the high demand for ultralow-temperature refrigeration units. In the current study, a CRS is built to generate a low temperature of -86°C for the storage of COVID-19 vaccines. In the CRS, the natural refrigerant combination R290-R170 is used as high-temperature and low-temperature fluids. The pull-down performance of the -86°C freezer is explored experimentally, and the stable operating performance is determined at two different dry bulb and wet bulb temperatures. Various status monitors are set up to analyze the CRS's operation features, and several temperature monitors are put in the freezer to analyze temperature variations. The power consumption of the CRS is examinedand evaluated. Finally, several key findings are summarized. The current work is the first to involve experimental measurements on -86°C temperature generated by a CRS, which can substantially enhance experiment data in ultralow-temperature refrigeration and contribute to a more in-depth understanding of the operation performance of a -86°C ultralow-temperature freezer.

Probabilistic neural network-based diagnosis of blockage faults in air conditioning and refrigeration units

Abstract The refrigeration unit is a core component of the air conditioner, and its typical faults are pipe scaling and blockage, which can cause refrigerant leakage in serious cases, and these faults can affect the cooling effect of the air conditioner and even affect the safety of using the air conditioner in serious cases. Therefore, it is necessary to study the fault diagnosis system of the refrigeration unit. The traditional fault diagnosis system for refrigeration units, which generally uses wireless sensor networks to transmit data, is a challenge because of its slow diagnosis speed and the low accuracy rate of fault diagnosis for refrigeration units. This paper uses a probabilistic neural network (PNN) to debug a blockage fault diagnosis algorithm system for simulated fault training. The system successfully achieves four levels of pre-warning for blockage faults: “uncertainty, micro-blockage, blockage, and severe blockage”, with the fastest pre-warning time of “uncertainty, micro-blockage” being less than 2 seconds. The experimental results of this paper show that the PNN system can take timely measures against blockage faults, and the fault diagnosis accuracy of the model reaches 97.97%, which is 13.34% higher than the traditional fault identification algorithm. The PNN model can pinpoint the blockage faults of the refrigeration unit, which enables the working state of the refrigeration unit to be continuously optimized, and the air conditioner to maintain energy-efficient operation. The fault simulation of the air conditioning refrigeration unit in automatic control mode verifies the blockage fault diagnosis’s accuracy and the algorithm’s feasibility, providing reference and learning for the development of fault diagnosis algorithms.

Comprehensive performance analysis of cold storage Rankine Carnot batteries: Energy, exergy, economic, and environmental perspectives

Rankine Carnot batteries have demonstrated promise as a viable solution for electricity storage due to their high energy density at low temperatures. A specific variant of these batteries, known as the Cold Storage Rankine Carnot Battery (CSRCB), utilizes a vapor compression refrigeration (VCR) unit to store cold energy at sub-ambient temperatures. In this paper, three different configurations of CSRCB are constructed: the Basic CSRCB (B-CSRCB), CSRCB with a recuperator in VCR (R-CSRCB), and CSRCB with a recuperator in VCR and a preheater in ORC (RP-CSRCB). The system is analyzed from four perspectives: energy, exergy, economic, and environmental (4E). The impact of key parameters, such as heat source temperature, ambient temperature, and pinch point temperature, on the system's performance is evaluated. The results indicate that the RP-CSCBR configuration outperforms others in terms of energy, exergy, and economic analysis. The evaporator in ORC-subsystem is the component with the largest exergy loss. When the three configurations of CSRCB achieve the maximum exergy efficiency under different conditions, the ORC-subsystem evaporator accounts for 41.9 %, 41.9 % and 17.6 % of the exergy loss of B-CSRCB, R-CSRCB and RP-CSRCB, respectively. The lowest levelized cost of storage (LCOS) can be obtained when the system is operating at high heat source temperature, low ambient temperature and small pinch temperature difference. The environment assessment results show that the changes of the key parameters of the system have different effects on the annual emission reduction (AER) and total equivalent warming impact (TEWI) of CSRCB with different configurations.

Hot melt extrusion with low-temperature deposition-coupling control improves the 3D printing accuracy of gelatin/fish pulp recombinant products

The flow properties of original materials directly affect the shape customization of 3D printing. In order to improve the molding quality, the 3D printing equipment was developed, which was characterized by a variable pressure and temperature extrusion unit, a numerical control transmission unit, an extrusion refrigeration unit, and a control box. The optimal pretreatment condition of sturgeon skin was 0.015 M phosphoric acid with higher gel strength (739.27 g), which could be a good substitute for commercial gelatin. The 7% gelatin/fish pulp reconstituted system could exhibit optimum printing properties through an improved 3D printer. The reconstituted system displayed a smoother printing process and superior accuracy during the process of 3D printing, and showed higher apparent viscosity and modulus during the process of cooling and molding. Additionally, the network structure of 3D printing products of reconstituted the gelatin/fish pulp was denser, which showed higher water holding capacity (89.03%), higher hardness (775.64 g), and constant elasticity (0.9853).

Experimental Study of the Heat Flow and Energy Consumption during Liquid Cooling Due to Radiative Heat Transfer in Winter

Radiation cooling is a passive energy saving cooling technology. The process of cooling heat transfer liquid due to the combined effect of night radiative cooling and convection of air at negative temperatures (in winter) is studied. The radiator used for cooling was built into the roof of the building. Its radiating plate was made of a steel sheet coated with zinc oxide. In it, heat dissipation was carried out both from the upper and lower sides of the radiating plate. The experimental values of the heat flux ranged from 20 to 80 W·m−2 at a temperature difference between heat transfer liquid and air from 5 to 15 °C and ambient air temperature from −17 to +5 °C. The correctness of the model for calculating the heat flux in winter conditions was confirmed. A theoretical calculation showed that, in winter, the heat flux removed by the radiator will be 15% less than the heat flux in summer. The amount of heat transferred per watt of electrical power of the refrigeration unit reached 8 W·W−1. To keep the refrigeration unit with radiative heat transfer more efficient than in a conventional vapor compression chiller, the heat transfer liquid temperature should be 6 °C above the atmospheric temperature air. The results of the study show that radiative cooling can be used in winter and may be useful for the development of energy-efficient cooling systems for various purposes (air conditioning, industrial cooling systems and fruit storage chambers).

THE USE OF ALTERNATIVE ENERGY SOURCES FOR THE OPERATION OF ENGINEERING SYSTEMS OF DETACHED CONSUMERS

The operation of many of the engineering systems that are necessary for the functioning of a detached residential building depends on specific sources of alternative energy, the use of which can significantly reduce the consumption of traditional fossil energy resources. A review of scientific works devoted to the operation of engineering systems using alternative energy sources is given. Several schemes of power equipment have been developed to obtain thermal and electrical energy supplied to isolated consumers. When designing a fixed technical solar system using solar radiation for operation, the locations of all power equipment, the solar receiver pitch on the roof of the building and the values of its optimal angle of inclination to the horizon were determined. A scheme of a small transportable hydroelectric power plant has been developed, which generates electric energy using the pressure created by the flow of water. A thermal refrigeration unit is designed, which uses the heat of the air removed from the animal stall to heat the heated medium.

A new biomass-natural gas dual fuel hybrid cooling and power process integrated with waste heat recovery process: Exergoenvironmental and exergoeconomic assessments

The integration of gas turbine cycle (GTC)-based energy processes with a biomass gasification process employing a post-combustion approach, in addition to improving the reliability and performance of the energy cycle, can reduce the current crisis in the energy sector and balance the environmental impacts of the hybrid energy cycle. The present paper develops a multi-criteria evaluation and optimization of a novel hybrid cooling and power process (HCPP) based on GTC and post-combustion-based biomass gasification process integrated with downstream cycles. Two fuels (i.e., natural gas and biomass) are utilized simultaneously to produce energy in the proposed process. In addition, the downstream cycles are based on two organic Rankine cycles (ORCs) and a refrigeration unit to recover waste heat. The performance of the developed HCPP has been evaluated and discussed from the thermodynamic-conceptual, exergoenvironmental and exergoeconomic points of view. Additionally, a tri-objective optimization is applied to identify optimal inputs and outputs variables. The overall results indicated that the proposed HCPP can produce 13 MW of electric power and 7.6 MW of cooling load. The thermal and exergy efficiencies of the system were 70.1% and 42.85%, respectively. Moreover, the values of levelized cost of energy (LCOE) and product unit environmental impact (PUEI) were calculated as 0.0748 USD/kWh and 0.0184 Pts/kWh, respectively. However, under tri-objective optimization, the values of LCOE and PUEI can be reduced by approximately 9.4% and 16.8%. The effect of different parameters was also discussed and evaluated through a parametric analysis. Furthermore, the conceptual assessment and design of the solar field was developed for a hypothetical scenario and configuration (based on geographical conditions of a certain region).

Comprehensive experimental performance study on a small-capacity transcritical R744 vapour-compression refrigeration unit equipped with an innovative ejector

Ejector-equipped transcritical R744 condensing units are believed to lead to a low-to-zero commercial refrigeration sector. In order to overcome the persisting barrier to their wider adoption represented by the lack of an affordable ejector control technique, the novel pulse-width modulation (PWM) ejector, being low cost, simple and invulnerable to clogging was recently implemented. However, additional experimental evaluations are needed. Therefore, in this experimental work the performance of two PWM ejector-equipped transcritical R744 condensing units, i.e. with and without overfed evaporator, was carried out. The experimental assessment was implemented at the medium temperature (MT) of about -5 °C, heat sink temperatures from 30 °C to 40 °C and compressor speeds from 40 Hz to 60 Hz.The outcomes obtained revealed that the PWM ejector can effectively control the high pressure in transcritical operating conditions, regardless of the selected heat sink temperature and compressor speed. In addition, at the same cooling capacity, the PWM ejector-equipped R744 system was found to permit energy savings between 7.0% and 11.1% without overfed evaporator and between 11.5% and 16.3% with overfed evaporator compared to the standard R744 unit (i.e. with vapour by-pass valve and without ejector), respectively. Finally, higher values of coefficient of performance (COP) were found to be offered by the PWM ejector compared with its today's available competitors.

SELECTION OF THE OPTIMAL HEATING COOLANT FOR ARM DEPENDING ON THE TECHNICAL CONDITIONS OF THE OIL AND GAS ENTERPRISE

Generation of cold is great demand process for many enterprises of the oil and gas industry. With large capacities of the enterprise, deeper cooling of heat carriers is required in chemical and petrochemical industries, metallurgy, compressor stations, etc. In administrative buildings and workshops located on the sites, it is required to create comfortable conditions in the buildings for the people who are there. In this regard, the demand for refrigeration units is increasing. Until recently, steam compression refrigerating machines were the market leader in refrigeration units. However, their main disadvantage is the high consumption of electricity, and often the process of generating cold has become too expensive.Relatively recently, steam compression refrigerating machines (chillers) have been replaced by absorption refrigerating machines (ARM). Their main and key feature is that they generate cold without consuming a single kilowatt of electrical energy, since the process of generating cold is based on the thermophysical properties of low-boiling solutions of lithium bromide or ammonia.

АНАЛИЗ ОТКАЗОВ ПРИ СЕРВИСНОМ ОБСЛУЖИВАНИИ И РЕМОНТЕ ХОЛОДИЛЬНЫХ УСТАНОВОК

The analysis of malfunctions in the support manning and repair of refrigeration units in processing fields of the agricultural-industrial complex and trade enterprises is presented. The main causes of malfunctions are identified. The structure and distribution of malfunctions during the operation of refrigeration units were established.

Investigation of Changes in Packaging Properties of Refrigerated Food Products

This study presents the experimental investigations of the thermal conductivity properties of refrigerated packages in an autonomous commercial open refrigerated display cabinet. The study aimed to determine whether the type of packaging can reduce the impact of a malfunctioning refrigeration unit on the product. The characteristics of refrigerated packages are studied during the freezing process on the level of loading and the arrangement of the packages in the display case. For the research, four types of packaging were used: combined, composite, plastic, and pulp. Based on the results obtained, the compliance of the packages with the established/existing requirements was determined during each test. It was found that during the refrigeration process, the permissible temperature norms in the case of individual packages complied with the most commonly used. None of the test packages met the norms during refrigeration by filling the products to the intended limit. As a result, simplified labeling of the respective cooling zones is proposed, and the issue of ensuring the uniformity of the cooling itself remains open. Given the cost of production, it is also proposed to take into account this issue (marking the corresponding cooling zones) when designing similar refrigeration equipment.

Theoretical analysis of a direct-coupled Stirling combined cooling and power system for heat recovery

The Stirling CCP (combined cooling and power) technology is an effective way to realize cooling and power cogeneration, but it still faces problems of complicated structure and large vibration. To relieve these issues, in this work, a direct-coupled Stirling CCP system with a simple structure is proposed and analyzed through the aid of a verified numerical model. In such a system, a thermal buffer tube is used to couple the engine unit and the refrigeration unit so that only two pistons are employed. To investigate the influence of varying working conditions, the output characteristics with different external resistances and operating temperatures are analyzed. In the optimal case, the system can provide a cooling capacity of 4042 W and an electricity power of 467.4 W with an exergy efficiency of 27.6%, when the heating, ambient and cooling temperatures are 300 °C, 30 °C and 10 °C, respectively. The results demonstrate that, compared with the conventional Stirling CCP systems, the presented system not only has a simpler structure, but also possesses superiority in both volumetric specific electricity power and exergy efficiency, which indicates its potential for cooling and power cogeneration driven by waste heat.

Thermo-economic assessment of sub-ambient temperature pumped-thermal electricity storage integrated with external heat sources

Thermally integrated pumped-thermal electricity storage (TI-PTES) offers the opportunity to store electricity as thermal exergy at a large scale, and existing studies are primarily focused on TI-PTES systems based on high-temperature thermal energy storage. This paper presents a thermo-economic analysis of a “cold TI-PTES” system which converts electricity into cold energy using a vapor compression refrigeration (VCR) unit and stores it at sub-ambient temperatures during the charging process, and generates electricity by using an organic Rankine cycle (ORC) working between the sub-ambient temperature and an external low-grade heat source during the discharging process. The effects of key parameters, i.e., mass flowrate and temperature of the storage medium, ORC evaporation temperature, component efficiencies, and pinch-point temperature differences, on the system performance are evaluated based on a whole-system thermo-economic model. The results reveal that the roundtrip efficiency and levelized cost of storage (LCOS) of the system increases while the electrical energy storage capacity decreases as the temperatures of the two cold storage tanks approach each other. When the temperature of the cold storage tank 1 rises from 1 °C to 8 °C while the cold storage tank 2 remains as 13 °C, there is an increase of 25% and 20% in the roundtrip efficiency and LCOS respectively while the energy storage capacity decreases by 69%. A roundtrip efficiency of 0.74 and LCOS of 0.32 $/kWh are achieved with a heat source temperature of 85 °C, using a mass flowrate and temperature of the cold storage medium of 50 kg/s and 1 °C. Furthermore, any change in cold storage medium mass flowrate changes both electrical energy storage capacity and power output by the same proportions. With a continuous high-flowrate external heat source, the LCOS can be as low as 0.17 $/kWh. By providing sufficient heat from an external heat source, the proposed system possesses a high potential for medium-to-large scale energy storage with a unique hybrid nature for electricity storage and thermal integration.

Multi-criteria sensitivity study and optimization of an electricity/cooling/hydrogen production scheme combined with SOFC-based sequential heat recovery: Sustainability and economic analyses

The establishment of new multigeneration processes is comparable and assessable from the sustainability viewpoint. Indeed, the sustainability approach assists the economic analysis leading to appropriate combination methods. Concerning the energetic flow exhausting a solid oxide fuel cell system, this study proposes an innovative trigeneration process with high sustainability index utilizing three stages of sequential heat recovery. The process encompasses a two-stage Rankine cycle boosted by a thermoelectric generator and an ejector refrigeration unit, and a polymer electrolyte membrane electrolyzer. This system is simulated in engineering equation solver software and a comprehensive sensitivity study is accomplished. It is concluded that the most influential parameter in the whole framework is the operational temperature of the stack and in the integrated process is turbine 1 pressure. Afterward, an advanced evolutionary optimization method is employed using the MATLAB software, and the optimal point is designated from the sustainability and economic standpoints. The optimal state reveals the sustainability index of 2.61 and total unit cost of 35.93 $/GJ, improved by 12.5% and 3.8% against the base case, respectively. Besides, the electric power, cooling, and hydrogen are correspondingly produced at 389.4 kW, 112.4 kW, and 0.45 kg/h, resulting in exergy efficiency and exergoeconomic factor of 57.75% and 52.1%, respectively.

THE PRINCIPLE OF OPERATION OF THE REFRIGERATOR IN CASE OF MALFUNCTION

Currently, the use of artificial cold is one of the main factors of economic, environmental and social life of the world. Any modern science, technology and technology cannot provide without artificial cold. And artificial cold is implemented with the help of refrigeration units. The article discusses the principles of operation of the refrigeration unit in the optimal mode of operation and in case of a malfunction of the heat exchanger. Various problems were compared with the optimal mode of operation and conclusions were given. All research work was carried out experimentally, as well as proved by a thermal imager (thermal imager). Detailed data were presented in the form of tables and diagrams. As a result of the analysis of the data, the use of a multi-factor experimental method was revealed. Individual and generalized conclusions were made on the processes of the refrigerator in each case of a malfunction.

Theoretical performance studies on environment friendly refrigerants used in refrigeration units

European Union regulations stipulate that household refrigeration systems must operate with fluid refrigerants that possess low global warming potential (GWPs). In this work, theoretical performance of six binary and one ternary mixture (which consists of R13I1, R290, R161, R32, R1234yf, and R1234ze(E)) was investigated. The performance parameters such as coefficient of performance (COP), refrigeration effect (RE), volumetric cooling capacity (VCC), discharge temperature, pressure ratio, and specific power consumption of all considered refrigerant mixtures is studied with respect to the evaporator temperature range of -18 to 180C and the condenser temperature range of 40 to 550C. The properties corresponding to different operating conditions for the refrigerants considered in this study are estimated using REFPROP 10. The findings demonstrated that, when compared to R134a, all the investigated refrigerants exhibited very low specific power consumption (apart from M9, M10, and M14-M16), and high volumetric cooling capacity (VCC) (apart from M11 and M13) under the operating conditions of evaporator temperature -180C and condenser temperature 400C. M1-M3 and M11-M13 gave similar and within 10% deviation in coefficient of performance, while M3 and M11-M13 refrigerant mixtures offer significantly low discharge temperatures when compared to R134a. Refrigerant mixtures M2 and M11 consistently exhibited a better performance in comparison to R134a in the aspect of majority of the performance parameters considered in this study. Finally, it is understood that M2 and M11 are two possible alternative refrigerants to conventional refrigerants used in small refrigeration units (R134a and R22). Further, it is also identified that these mixtures are non-flammable, possess zero ODP and low GWP values.

Redesigning a Solar PV Kiosk in High-Temperature Environments of Burundi, Africa

Solar PV systems in Africa are installed in high-temperature environments ranging from 25 °C to 40 °C. Experience and the literature note that these systems frequently fail a few years after installation and require the replacement of essential components such as PV panels, inverters, or batteries. In Burundi, batteries operating in high-temperature environments with a designed shelf life of 15 years are being replaced every 4 years due to thermal runaway. The motivation of this paper was to redesign a 45 kWh/day multi-use solar PV kiosk in Ruhoro, Burundi, Africa, so as to improve its sustainability. Using original primary field data, the project calculated a mean energy demand at the Ruhoro PV kiosk of 14.50 kWh/day in 2022 and a forecasted demand of 16.50 kWh/day in 2025. The kiosk is designed to supply 20.25 kWh/day after losses, which is sufficient for the current and future demand. The paper reviewed the impact of high-temperature environments on both solar PV panels and batteries. Results indicated only a 13% reduction in power output in the solar PV panels and a 60% reduction in the shelf life of acid gel batteries from 15 years to 6 years when exposed to temperatures of between 25 °C to 40 °C. To improve the shelf life of the batteries, the paper researched different cooling technologies for batteries. These included water cooling, fan cooling, and refrigeration cooling. Using engineering modelling formulae, the paper observed that the application of a fan cooling system resulted in an improvement in the product life of the batteries by 4 years and a refrigeration cooling system by 9 years. The paper concluded that using a refrigeration cooling system in the Ruhoro solar PV kiosk was appropriate and requires an additional 5.28 kWh/day. Factoring in this additional demand, the refrigeration cooling still reduced the lifecycle CAPEX cost from USD 94,625 to USD 72,875 over a 15-year period. The inclusion of a refrigeration cooling system also improved the net present value (NPV) cost effectiveness over a 15-year period from USD—62,481 to USD 4893. This is a net profit of almost USD 5000 if a refrigeration unit is installed. The paper therefore recommends the use of refrigeration cooling systems as appropriate for high-temperature environments such as the Ruhoro solar kiosk. It concludes that the refrigeration system is a cost-effective option for long-term sustainable use for communities in Africa living in high-temperature environments.

HIGH PERFORMANCE TECHNOLOGIES USED IN FUSHENG SCREW COMPRESSORS 
 AUTHORS

In the context of negative changes occurring in the planets biosphere, such as pollution of the environment and the atmosphere, global warming, and depletion of energy resources, increasingly high criteria are imposed on manufacturers of refrigeration equipment, the most important of which are: (a) enhancement in the energy efficiency of refrigeration equipment; (b) decrease of material consumption of refrigeration units, and (c) use of clean and safe materials and refrigerants.
 The Taiwanese company, Fusheng, has been one of the world leaders in the production of screw refrigeration compressors for several decades. The experts at the company are always working to enhance the manufactured equipment and implement the most cutting-edge technologies.
 Recently, the most effective steps in this area have been the advancement and mastering of the manufacturing of special two-stage low-temperature screw compressors of the SRT series, as well as the production of compact screw compressors with an integrated BSR series oil separator with a variable compression ratio and semisealed screw refrigeration compressors with a volumetric capacity of 85 m3/h to 1946 m3/h
 The SRT compressor series consists of six types, with a first-stage volumetric capacity of 120759 m3/h and a second-stage volumetric capacity of 50300 m3/h