Cascade Refrigeration Cycle Research Articles

Analytical study on core flow in a novel scheme of cascade heat exchanger intensified with open foam partially filled in an annulus

Due to the importance of energy-saving and efficiency in the industry, a novel scheme for waste heat recovery was utilized in the cascade refrigeration cycle. This system is composed of a cascade heat exchanger combined with a recuperator intensified with open foam. The exhaust air from the heat exchanger is used for the air handling unit. Also, core flow in an annular channel is proposed as an innovation to enhance heat transfer. An analytical study was performed to evaluate the impact of metal foam properties on the performance of the partially filled annular heat exchanger with asymmetric isothermal boundary conditions. The energy equations were decoupled by normalizing, linear combination, and the variable change method. Then by forming the Bessel differential equations, temperature solutions were achieved in terms of the modified Bessel functions of the first and second kinds. In the energy and momentum equations of the porous region, the local thermal non-equilibrium (LTNE) and the Darcy-Brinkman models were used, respectively. The analytical solutions of velocity, pressure drop, mass flow ratio, temperature, and Nusselt numbers were obtained. A hydraulically critical point exists at the nondimensional interfacial radius of 2.86 for Da=10−4. It revealed that the Darcy number and the thermal conductivity ratio are two crucial parameters for improving performance. Based on the Performance evaluation criterion (PEC) definition, the optimal porosity value of 0.91 was determined. Also, a design triangle in the range of metal foams was proposed to select the local Nusselt and Biot numbers. At a particular Biot number, the PEC value increases 3.76 times in the design range of metal foams. Results demonstrated that the core flow in an annular heat exchanger leads to high performance, several times greater than non-core flow.

Analysis of energy, economy, and carbon emission of nested cascade refrigeration cycle with heat recovery system

Condensation heat recovery is a way to save energy and reduce carbon emissions. For the auto-cascade refrigeration cycle system, increasing the heat recovery temperature is contradictory to ensuring the refrigerate performance of the system. Here is a nested cascade refrigeration cycle system with a heat recovery system is designed to increase the heat recovery temperature. Carry out energy, economy, and carbon emissions analysis of the system. In the economic analysis, the impact of carbon tax trading policies was considered. The analysis results show that when cooling 1 kgR23 consumes the same energy and obtains the same heat supply when the recovery temperature of the auto-cascade refrigeration cycle reaches 50°C, the recovery temperature of the heat recovery system is 67°C, which increases the recovery temperature by 17 °C. Without considering carbon tax transactions, when the recovery temperature is lower than 100 °C, the economy of the heat recovery system is better than that of standard coal; and when the recovery temperature is higher than 100 °C, the economy of standard coal is better. When considering the impact of carbon tax transactions, when the heat recovery temperature is below 110 °C, and the heat recovery system is the most economical. Among them, when the condensation temperature of R744 rises from 50 °C to 120 °C in the heat recovery system, the carbon dioxide emissions increase from 20.8 kg/GJ to 45.84 kg/GJ. In the temperature range of 50–120 °C, it is lower than electric heating, standard coal heating, and natural gas heating.

A Critical Analysis of Natural Gas Liquefaction Technology

Liquefied natural gas (LNG) is an important energy source and occupies an important proportion in natural gas consumption, therefore, the selection of appropriate liquefaction processes and related optimization should be seen as subjects of great importance. Accordingly, in the present review, we provide a comparative and critical analysis of the current status of natural gas liquefaction technology through examination of the advantages and disadvantages associated with three natural gas liquefaction processes (namely, the cascade liquefaction cycle, the expander-based cycle and the mixed refrigerant cycle). It is shown that the energy consumption related to the cascade refrigeration cycle is the lowest. Compared with it, the mixed refrigerant cycle has the advantages of being a simpler process, with less units, low investment cost and low requirements in terms of refrigerant purity. The expander-based cycle can be started and stopped quickly and simply, but the power consumption is relatively high.

Thermoeconomic Evaluation and Optimization of Using Different Environmentally Friendly Refrigerant Pairs for a Dual-Evaporator Cascade Refrigeration System

Applications of dual-evaporator refrigeration systems have recently gained much attention both in academia and industry due to their multiple benefits. In this study, a comprehensive thermodynamic and economic analysis is conducted to evaluate the potential of using several environmentally friendly refrigerant couples and identifies the most suitable one yielding the best economic results. To achieve this goal, a detailed parametric study is conducted, and an optimization process is performed using a particle swarm optimization (PSO) approach to minimize the unit production cost of cooling (UPCC) of the cascade refrigeration system. The results showed that among all selected 18 refrigerant pairs and for all ranges of examined operating parameters, the R170-R161 pair and R1150-R1234yf pair are identified as the best and worst pairs, respectively, from both thermodynamic and economic viewpoints. The results also confirm that R170-R161 pair has an improvement over R717-R744, used as a typical refrigerant pair of cascade refrigeration cycles. For a base case analysis, the COP of R170-R161 and R1150-R1234yf pairs is determined as 1.727 and 1.552, respectively, while their UPCC is found to be $0.395/ton-hr and $0.419/ton-hr, respectively, showing the influence of proper selection of refrigerant pairs on the cascade cycle’s performance. Overall, this study offers a useful thermodynamic and economic insight regarding the selection of proper refrigerant pairs for a dual-evaporator cascade vapor compression refrigeration system.

Cogeneration of power and hydrogen using Scramjet cooling system :Energy and exergy analyses

In the current study, a new integrated system is provided to prevent waste energy and reduce power consumption. This system consists of a cascade refrigeration system (for cooling) and an Organic Rankine cycle(ORC) (for power generation). These two cycles are combined through a heat exchanger. In fact, this heat exchanger acts as a condenser for the cascade refrigeration cycle and evaporator for ORC. The waste heat of the cascade refrigeration cycle is used to handle the ORC. In this way, a part of the power consumption of the cascade refrigeration cycle is satisfied by ORC. Thermodynamic simulation of the proposed system is carried out via Engineering Equation Solver(EES) software. A parametric study is done to evaluate the effects of the operational parameters on the performance of the integrated system. In addition, different working fluids are used in cascade refrigeration and ORC cycles. The results showed that by using the working fluids of R245fa, R717, and R141b in order in the low-temperature refrigeration cycle, high-temperature refrigeration cycle and ORC, one can produce cooling at -50 ° C and also reduce the power consumption up to 48.69% in the cascade refrigeration cycle.

An integrated dimensionality reduction and surrogate optimization approach for plant‐wide chemical process operation

AbstractWith liquefied natural gas becoming increasingly prevalent as a flexible source of energy, the design and optimization of industrial refrigeration cycles becomes even more important. In this article, we propose an integrated surrogate modeling and optimization framework to model and optimize the complex CryoMan Cascade refrigeration cycle. Dimensionality reduction techniques are used to reduce the large number of process decision variables which are subsequently supplied to an array of Gaussian processes, modeling both the process objective as well as feasibility constraints. Through iterative resampling of the rigorous model, this data‐driven surrogate is continually refined and subsequently optimized. This approach was not only able to improve on the results of directly optimizing the process flow sheet but also located the set of optimal operating conditions in only 2 h as opposed to the original 3 weeks, facilitating its use in the operational optimization and enhanced process design of large‐scale industrial chemical systems.

Energy and exergy analysis of a combined system: cascade organic Rankine cycle and cascade refrigeration cycle

In this paper, a new combined system is proposed for recovering thermal energy at medium temperature using a cascade organic Rankine cycle to feed a cascade refrigeration cycle. Energy and exergy analysis is applied to the combined system to determine its performance using different working fluids under the same operating conditions taking into account the effect of some operating parameters and the selection of organic fluids on cycle performance. The pair of organic fluid (Toluene/R245fa) used for the cascade organic Rankine cycle and the pairs (R717/R744, R717/R23, R134a/R23) used for the cascade refrigeration cycles. The results show that the combined system function with the couple (R717/R23) for cascade refrigeration cycle gives better exergy efficiency 50.03% compared to other couples, 49.57% for the couple (R717/R744), and 48.01% for the couple (R134a/R23). The thermodynamic evaluation shows that the operating temperatures, such as the cascade organic Rankine cycle evaporation temperature and the cascade refrigeration cycle evaporation temperature influence the performance of the combined system.

Experimental study on performance of double-mode refrigeration system

To ensure energy-saving and environment-friendly operation of multifunctional cold storage refrigeration systems, an experimental platform for a double-mode refrigeration system (DMRS) has been built, which can realize both a single-compression refrigeration cycle (SRC) and a cascade refrigeration cycle with a single refrigerant (CRC). The variable-frequency characteristics and control strategy of two modes were experimentally studied. The results show that with an increase in the low-temperature stage compressor frequency, there exist an optimal COP and optimal compressor frequency, the optimum frequency increases with a decrease in evaporation temperature and condensation temperature. When the condensation temperatures are 45, 40, and 35 °C, the evaporation temperature switching values of the refrigeration capacity are 2.5, −1.2, and −4.1 °C, respectively, and the evaporation temperature switching values of the COP are −10.6, −15.0, and −19.1 °C, respectively; and a control strategy of mode switching and compressor frequency adjustment is summed. When the system is running between two modes, the compression ratio is below 6, the discharge temperature is below 100 °C, and as the evaporation temperature increases from −35 °C to 10 °C, the COP of the system at 45 °C, 40 °C and 35 °C varies from 0.98 to 3.54, 1.20 to 4.27 and 1.42 to 5.20 respectively.

Thermodynamic performance study on a novel absorption‐ compression cascade refrigeration activated by an internal combustion engine

A novel cascade refrigeration system was presented and studied, which could supply low-temperature cooling capacity for fishing boats and refrigerated trucks at a low energy cost. The cycle was cascaded by a high-temperature stage of absorption-compression combined refrigeration cycle and a low-temperature stage of the CO2 subcritical compression refrigeration cycle. The presented cascade cycle could not only utilize adequately the waste heat of the engine but also utilize adequately the excellent performance of the CO2 subcritical cycle operating on a low-temperature working condition. The high-temperature stage cycle had three solution modes, which could bring about an effective waste heat utilization of the engine and effectively decrease power consumption. Based on the proposed cascade cycle, a fundamental thermodynamic model was constructed and solved under different operating modes. The obtained results indicated that the performance coefficient of the cascade refrigeration system could reach 3.26, which was significantly higher than 2.1 of the traditional two-stage compression cascade refrigeration system. Moreover, the exergetic efficiency of the cascade refrigeration system could reach about 0.52 under the conditions of evaporating at −35°C and condensing at 40°C. The research findings can provide an effective solution for the utilization of waste heat in refrigerated trucks and fishing boats. Novelty Statement The novelty of this work lied in that a novel absorption-compression cascade refrigeration cycle was proposed, which can supply low temperature cooling capacity for refrigerant trucks and fisher vessels by extremely utilizing the waste heat exhaust gases and jacket water from internal combustion engine of vehicles or ships.

Novel Cascade Refrigeration Cycle for Cold Supply Chain of COVID-19 Vaccines at Ultra-Low Temperature -80°C Using Ethane (R170) Based Hydrocarbon Pair

Several media report highlight on that the pharmaceutical companies require ultra-low temperatures -80°C to transport and store its COVID-19 vaccines. This research presents the thermodynamic analysis on cascade refrigeration system (CRS) with several refrigerant pairs which are R32/R170, R123/R170, R134a/R170, R404A/R170, R407c/R170, R410/R170, and the hydrocarbon (HC) refrigerant pair Propane/Ethane, namely R290/R170. Besides, the results of R22/R170 pair, which is not recommended to be used due to phase out of R22 as per Montréal Protocol, are included as base case to compare the novel hydrocarbon pairs in CRS and the old trend of refrigerant pairs. Thermodynamic properties of all these pairs were investigated and compared under different intermediate temperature used in CRS heat exchanger, which thermally connected both the Low and High temperature cycles (LTC) and (HTC). By applying the first law of thermodynamics, the coefficients of performance (COPs) and the specific power consumptions (SPC) in kW/TR are presented and compared. In addition, by applying the second law of thermodynamics the exergetic efficiencies were estimated. The results reveal the promising opportunity of using the HC pair (R290/R170). The minimum SPC in kW/TR is recorded for the pair R123/R170. One the other hand, the highest exegetic efficiency values are observed to be 40%, 38%, and 35% for the pairs R123/R170, R290/R170, and R134/R170, respectively. This research concludes that the HC pair (R290/R170) is highly recommended for CRS applications either to transport the COVID-19 or store it in cold storage rooms in hospitals and clinics. All precautionary measures should be carefully applied in design and operation of HC pair (R290/R170) due to its flammability hazard.

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Thermoeconomic analysis of a novel combined cooling, heating and power system based on solar organic Rankine cycle and cascade refrigeration cycle

This paper proposes a solar organic Rankine cycle integrated cascade refrigeration system to meet a hospital’s heating, cooling (each in two temperature levels) and electricity demands. The system is analyzed from energy, exergy and exergoeconomic point of view. Energy and exergy efficiency of the system calculated 89.39% and 8.70%, respectively. Exergy destruction rates of the system components are carried out and results reveal that the solar collector is the main source of irreversibility. The value of exergoeconomic factor for total system shows that the capital investment cost is more than the cost of exergy destruction. Collector is the main component from exergoeconomic point of view. The effect of ORC working fluid change, collector type, solar irradiation and ambient temperature are investigated. Cyclohexane from energy and exergy point of view and octane from exergoeconomic point of view are more efficient. The system with parabolic through collector indicates better results compared to the use of linear Fresnel reflector and parabolic dish collector. Increasing solar irradiation causes reduction in solar field area, energy and exergy efficiencies and total cost of the system. Increasing ambient temperature reduces solar field area and exergy efficiency, and improves thermal efficiency and the total cost of the system.

High-flux thermal management at megawatt scale using a double-effect absorption/vapor-compression cascade refrigeration cycle

Abstract A robust, high-performance, cascaded double-effect absorption/vapor-compression cycle with a high temperature lift was conceptualized and analyzed for a naval ship application. A double-effect LiBr–H2O absorption cycle driven by high-temperature (>275 °C) exhaust heat was coupled to a subcritical CO2 vapor-compression cycle to provide low temperature refrigerant (-40 °C) for high-heat flux electronics applications and medium temperature refrigerant (5 °C) for space conditioning and other low-heat flux applications. The double-effect absorption/vapor-compression cycle outperformed the corresponding single-effect cycle, providing 74.4% higher cooling capacity for the same waste heat input; however, it required more heat exchange area. The improved performance of the double-effect configuration was much higher at lower heat rejection temperatures. A parametric study on the exhaust and heat rejection temperatures showed that the cycle exhibited high COPs over a wide range of operating conditions, indicating the robustness of the cycle.

Performance optimization and parametric evaluation of the cascade vapor compression refrigeration cycle using Taguchi and ANOVA methods

In this study, a vapor compression cascade refrigeration cycle was evaluated for the first time by considering the statistical analysis methods, Taguchi and ANOVA approaches, for performance optimization. The analysis was carried out to achieve the optimum operating condition for the maximum COP and exergetic efficiency. The impacts of the operational parameters on the energetic and exergetic performances were investigated. The results show that the most influential parameter on the COP and exergy efficiency was the evaporator temperature, the condenser temperature of the lower cycle, condenser temperature of the overall system and isentropic efficiency of the compressor and the impact ratios were 58.1%, 14.4%, 10.25%, and 7.47%, respectively. The best condition for the multiple performance characteristics was decided to be A3B3C1D1E3F3G3H2J1K2. The COP and exergy efficiency within the range of the operating parameters in the evaluation were found to be 3.274 and 37.63%. These were greater than 27 different combinations of the thermodynamic evaluation results. The temperatures of the evaporator, condenser for the lower cycle, and condenser for the overall system have increment or decrement ratios of 3.92%/°C, 2.2%/°C and 1.61%/°C. The parametric evaluation corroborates the results of the Taguchi and ANOVA methods.

4E analyses and multi-objective optimization of cascade refrigeration cycles with heat recovery system

In this paper, thermodynamic simulation and analyses of cascade refrigeration and heat recovery cascade refrigeration cycles are investigated. Due to the high heat dissipation in the gas cooler in the cascade refrigeration cycle, the heat recovery cascade refrigeration cycle uses this heat to launch a Rankine cycle. R744 refrigerant for the high-temperature circuit and R744A refrigerant for the low-temperature circuit are used. Energy, exergy analyses for these cycles have been performed. Due to the better performance of the heat recovery cascade refrigeration system, advanced exergy, exergoeconomic, and exergoenvironmental, analyses have been performed for this cycle with Engineering Approach. In this regard, computer code was developed to compute these analyses. Multi-objective optimization of the cycle by the genetic algorithm has been performed with the objective functions of exergy efficiency and total product cost as well as the coefficient of performance and product environmental impact. Exergoeconomic analysis demonstrates that the product cost rate for the cycle is 3.4 $.h-1. Based on exergoenvironmental analysis, the compressor1 has the highest environmental impact. The optimization results reveal that using the heat recovery cascade refrigeration cycle leads to an increasing 7.6% coefficient of performance and 12.5% exergy efficiency.

메탄, 에틸렌 및 프로판 냉매를 활용한 다원 냉동 사이클에서 LNG 냉열을 활용한 동력 절감 방안에 대한 연구

메탄, 에틸렌 및 프로판 냉매를 활용한 다원 냉동 사이클에서 LNG 냉열을 활용한 동력 절감 방안에 대한 연구

Parametric analysis of a combined ejector-vapor compression refrigeration cycle

Abstract From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

Reducing the power consumption of cascade refrigeration cycle by a new integrated system using solar energy

In this paper, to prevent the waste energy and reduce the power consumption in cascade refrigeration cycle (CRC), a new integrated system, including CRC, solar cycle (SC) and organic Rankine cycle (ORC), is proposed. The waste energy in CRC is used to preheat the SC working fluid, thus, the total investment cost is reduced 20% (1099000 $) in comparison with the situation that the CRC’s generated heat is wasted. To investigate the proposed system, the energy, exergy, exergoeconomic and exergoenvironmental analyses were carried out. Considering 500 W/m2 solar radiation for 12 h in a day, it resulted that the coefficient of performance, the energy and exergy efficiencies, and exergoenvironmental impact improvement were obtained as 4.233, 84.53%, 37.05% and 0.6256, respectively. The main exergy destruction was related to solar collectors with 53.10% of total exergy destruction. The unit exergy cost of producing electricity, heating and cooling were calculated as 0.810 $/kWh, 1.395 $/kWh and 0.225 $/kWh, respectively. Meanwhile, the consumed power in the proposed system was reduced by 82.57% in comparison with conventional CRC. Finally, it should be noted that the proposed system could produce 132.72 m3/day hot water at 65 °C, and 2400 kWh/day cooling by consuming 567.01 kWh/day power.

Thermo-economic analysis of a novel hybrid multigeneration system based on an integrated triple effect refrigeration system for production of power and refrigeration

Multigeneration systems provide substantial benefits in terms of improving efficiency and economics as well as environmental benefits. In this study, a multigeneration system is proposed for generating power and triple effect refrigeration at different evaporation temperatures. The system hybridizes a 25 MW recuperative Brayton cycle with an organic Rankine cycle (ORC) and an integrated refrigeration system that combines a branched generator–absorber heat exchange (GAX) absorption refrigeration system with a dual-evaporator cascade carbon dioxide-ammonia compression refrigeration system. The exhaust gas from the Brayton cycle is divided into two streams: one is supplied to the generator of the GAX cycle and the remaining is supplied to the ORC for additional power generation. Results show that additional power generation by ORC increases thermal efficiency from 0.394 to 0.510 and reduces the levelized cost of electricity from $75.5/MWh to $64.4/MWh. The integration of GAX cycle and cascade cycle is beneficial from both thermodynamic and economic viewpoints. Due to their integration, the coefficient of performance of the cascade cycle increases substantially from 2.37 to 4.69. Also, the levelized cost of cooling for the production of triple effect refrigeration decreases from $0.08/ton-hr to $0.059/ton-hr. Environmental analysis shows that the development of multigeneration system can lead to avoiding 24,185 tons of CO2 per year. The proposed multigeneration system brings a possibility to efficiently recover the waste energy for additional power generation and refrigeration production at different temperatures. Waste energy recovery by the ORC and GAX cycle as well as the integration of the GAX cycle with a cascade refrigeration cycle provide good potential for cleaner production of all products with improved efficiency, economics and environmental benefit.

Performance Analysis of a Solar-Powered Multi-Effect Refrigeration System

The main objective of the current work is to investigate the thermodynamic performance of a novel solar powered multi-effect refrigeration system. The proposed cycle consists of a solar tower system with a heliostat field and central receiver (CR) that has molten salt as the heat transfer fluid, an absorption refrigeration cycle (ARC), an ejector refrigeration cycle (ERC), and a cascade refrigeration cycle (CRC). Energy and exergy analyses were carried out to measure the thermodynamic performance of the proposed cycle, using Dhahran weather data and operating conditions. The largest contribution to cycle irreversibility was found to be from the CR system (52.5%), followed by the heliostat field (25%). The first and second-law efficiencies improved due to the increase in the following parameters: ejector evaporator temperature, turbine inlet and exit pressures, and cascade evaporator temperature. Parametric analysis showed that the compressor delivery pressure, turbine inlet and exit pressures, hot molten salt outlet temperature, and ejector evaporator temperature significantly affect the refrigeration output.