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•Two different SOFC system configurations are considered for simulation.•Indexing of SOFC stack is evaluated for different types of refrigerated trucks.•Detailed thermoeconomic ...analysis is carried out for the combined system.•A comparison between refrigeration technologies in terms of GHG emissions is shown.
A vapour absorption refrigeration system (VARS) coupled with a solid oxide fuel cell (SOFC) is proposed for different types of refrigerated trucks (large, medium and small) as a favourable alternative to conventional diesel engine driven vapour compression refrigeration systems. An SOFC-supported VARS has the novel attributes of negligible environmental impact and the ability to keep the refrigeration system running while the vehicle engine is switched off. In addition, the SOFC system produces electricity which can be utilised for other operations on the vehicle. This in turn reduces the load on the main diesel engine of the vehicle. This research paper presents a comprehensive thermo-economic study for two different SOFC system configurations namely; series and parallel to optimise the SOFC sub-system layout. Moreover, a benefit function to optimise the SOFC stack size and operating conditions has been identified considering four performance parameters, namely; thermodynamic efficiency, mass of the system, greenhouse gas (GHG) emissions, and cost of cogeneration. The analysis was conducted on various categories of refrigerated trucks. The results show that a parallel configuration has an enhanced thermo-economic performance and requires a 45–65% lower number of SOFC cells to obtain the required refrigeration load in comparison to the series configuration. Simulation results indicated that the proposed SOFC-VARS for large, medium and small refrigerated trucks can provide an output of 3.3 kW, 12.8 kW and 18.7 kW of electric power and 1 kW, 4 kW and 6 kW of refrigeration load respectively. It was also found that the SOFC-coupled VARS is able to supply the required refrigeration load with negligible emissions of GHGs compared to other refrigerated transportation technologies.
Abstract International efforts to eradicate smallpox in the 1960s and 1970s provided the foundation for efforts to expand immunization programmes, including work to develop immunization supply ...chains. The need to create a reliable system to keep vaccines cold during the lengthy journey from the manufacturer to the point of use, even in remote areas, was a crucial concern during the early days of the Expanded Programme on Immunization. The vaccine cold chain was deliberately separated from other medical distribution systems to assure timely access to and control of vaccines and injection materials. The story of the early development of the vaccine cold chain shows how a number of challenges were overcome with technological and human resource solutions. For example, the lack of methods to monitor exposure of vaccines to heat during transport and storage led to many innovations, including temperature-sensitive vaccine vial monitors and better methods to record and communicate temperatures in vaccine stores. The need for appropriate equipment to store and transport vaccines in tropical developing countries led to innovations in refrigeration equipment as well as the introduction and widespread adoption of novel high performance vaccine cold-boxes and carriers. New technologies also helped to make injection safer. Underlying this work on technologies and equipment was a major effort to develop the human resources required to manage and implement the immunization supply chain. This included creating foundational policies and a management infrastructure; providing training for managers, health workers, technicians, and others. The vaccine cold chain has contributed to one of the world’s public health success stories and provides three priority lessons for future: the vaccine supply chain needs to be integrated with other public health supplies, re-designed for efficiency and effectiveness and work is needed in the longer term to eliminate the need for refrigeration in the supply chain.
•Studies on modelling and design of linear compressor were comprehensively reviewed.•Oil-free miniature linear compressor for electronics cooling has advantages.•Moving magnet linear motor is the ...major trend. Compatibility with ammonia is possible.•For mass production, minimum number of sensors and actuators are required.•Main challenge of commercialising the linear compressor is the cost.
Linear compressor has no crank mechanism compared with conventional reciprocating compressor. This allows higher efficiency, oil-free operation, lower cost and smaller size when linear compressors are used for vapour compression refrigeration (VCR) system. Typically, a linear compressor consists of a linear motor (connected to a piston) and suspension springs, operated at resonant frequency. This paper presents a review of linear compressors for refrigeration system. Different designs and modelling of linear compressors for both domestic refrigeration and electronics cooling (miniature VCR system) are discussed. Key characteristics of linear compressor are also described, including motor type, compressor loss, piston sensing and control, piston drift and resonance. The challenges associated with the linear compressors are also discussed to provide a comprehensive review of the technology for research and development in future.
•Conventional and advance exergy analysis are applied.•Splitting the exergy destructions is well illustrated.•Ejector should be firstly improved, followed by condenser then generator.•Condenser has ...the largest influence compared to generator and evaporator.•The system is largely improved by improving the ejector.
This paper presents a comprehensive investigation of an ejector refrigeration system using conventional and advanced exergy analysis. Splitting the exergy destruction within each system component into endogenous/exogenous and avoidable/unavoidable parts provides additional useful information and improves the quality of the exergy analysis. Detailed calculations of the exergy destruction parts are schematically illustrated. Conventional exergy analysis indicates that about half of the total exergy destruction is caused by the ejector and about one quarter occurs in the generator. The advanced exergy analysis reflects the strong interactions between system components. The ejector has the highest priority to be improved, followed by the condenser and then the generator. The temperature difference in the condenser has the largest influence on the exergy destruction compared to that in the generator and the evaporator, and the ejector efficiencies are also very crucial for the exergy destruction. The system performance can be largely enhanced through improvements of the ejector and the condenser as well as the generator.
A tri-generation layout is proposed in the paper, which is composed of a novel cascade power generation system, a transcritical CO2 compression refrigeration system (CCRS) with LiBr–H2O absorption ...refrigeration system (ARS) after-cooler, and a proton exchange membrane electrolyzer (PEME). The performance of the system is evaluated and optimized based on the thermodynamic and exergoeconomic principles. The cascade system consists of a modified Kalina cycle (MKC), an organic Rankine cycle (ORC), and a liquefied natural gas (LNG) subsystem, which is driven by a geothermal heat source. Employing the MKC in such cascade systems and using the absorption subcooling method for the CCRC in a tri-generation system have not been investigated in previous studies. The cooling system and PEME are correspondingly fed by the output power of the ORC and MKC while the output electricity is generated in the LNG subsystem. An optimum point was selected from two scenarios of tri-objective optimization using a hybrid Genetic-Fgoalattain algorithm. The optimization of the proposed system revealed an exergy efficiency of 26.5%, which is much higher than the values reported for the similar tri-generation systems in the literature. At the optimal point, the net output power, cooling rate, and hydrogen rate produced by the system are 451.8 kW, 297.8 kW, and 2.274 kg⋅h−1, respectively. Moreover, the payback period of the system is obtained as 2.385 years.
•A novel geothermal-driven tri-generation layout based on a cascade power system and a CO2 cooling system.•Thermo-economic optimization of the system using a hybrid algorithm considering two scenarios.•Higher exergy efficiency of the system compared to the similar tri-generation systems.•The exergy efficiency, power, and cooling rate are 26.5%, 451.8 kW, and 297.8 kW, respectively.•The payback period of the system is obtained as 2.385 years.
In this paper, the advanced exergy analysis was applied to a R744 booster refrigeration system with parallel compression taking into account the design external temperatures of 25 °C and 35 °C, as ...well as the operating conditions of a conventional European supermarket. The global efficiencies of all the chosen compressors were extrapolated from some manufactures' data and appropriated optimization procedures of the performance of the investigated solution were implemented.
According to the results associated with the conventional exergy evaluation, the gas cooler/condenser, the HS (high stage) compressor and the MT (medium temperature) display cabinet exhibited the highest enhancement potential. The further splitting of their corresponding exergy destruction rates into their different parts and the following assessment of the interactions among the components allowed figuring out the real achievable improvements. The avoidable irreversibilities of the HS compressor and that of the MT evaporator were mainly and completely endogenous, respectively. On the other hand, the gas cooler/condenser could be predominantly improved by decreasing the inefficiencies of the MT evaporator. As regards the auxiliary compressor, large enhancements were attainable through the drop in the irreversibilities occurring in the remaining components.
•Advanced exergy analysis of a commercial R744 refrigeration system is implemented.•Evaluated solution employs the parallel compression technology.•Avoidable exergy destruction of the investigated system is mostly endogenous.•Gas cooler exhibits a largely negative mexogenous destruction rate.•HS compressor and MT evaporator should be enhanced.
Advanced exergy analysis was carried out for absorption-compression refrigeration-cycles with a working fluid selection and parametric analysis. The exergy-destruction was split into ...endogenous-exogenous and avoidable-unavoidable-parts to reveal the interdependency within the components and determine the improvement potential. The results show that the largest exergy-destruction occurs in the generator, accounting for 53.8% of the total destruction. The largest irreversibility occurs for R507a/NH3–H2O while the lowest destruction occurs for R152a/NH3–H2O with an approximate reduction of 0.62 kW. The largest irreversibility occurs in the azeotropic-fluids while the lowest occurs in wet fluids. More than one-half of overall exergy-destruction rates of the systems falls into the part of the avoidable-destruction with 52.5% of overall irreversibility. The major part of the avoidable-destruction occurs in the generator with 11.47 kW and it accounts for 57.8% of the total avoidable part, meaning that it has the highest improvement potential. The parametric analysis of the advanced exergy shows that the avoidable-part of the exergy-destruction can be minimized to a considerable extent employing a temperature of the condenser below 40 °C and generator temperature larger from 100 °C.
•An advanced exergy analysis for the cascade refrigeration system is performed.•The exergy destruction is split into endogenous, exogenous, avoidable and unavoidable parts.•Parametric optimization and working fluids selection of the system is carried out.•The avoidable exergy destruction is minimized with optimum operation conditions.
Nowadays, the magnetic materials with special functional characteristics are played very important roles in the development of our present modern society. The magnetic refrigeration (MR) technology ...which is based on the magnetocaloric effect (MCE) of magnetic solids has been considered as an energy-efficient alternative method to our present well used gas compression/expression refrigeration technology. The commercial products of magnetic refrigerators are still in the developing stage, searching and designing magnetic solids with outstanding MCE performances is one of the most important tasks at present. This paper briefly reviewed our recent progress in the investigation of the crystal structure, magnetic properties and magnetocaloric performances in several series of binary and ternary rare earth (RE) based intermetallic compounds. Some of them have been found to exhibit promising magnetocaloric performances at low temperatures which make them be considerable for cryogenic MR application.
•Our recent progress related to MCE in RE-based intermetallic is reviewed.•Structural, magnetic and magnetocaloric properties are summarized.•Some of them exhibit promising cryogenic magnetocaloric performances.•Some of them are considerable for cryogenic magnetic refrigeration.
Magnetic refrigeration is a fascinating superior choice technology as compared with traditional refrigeration that relies on a unique property of particular materials, known as the magnetocaloric ...effect (MCE). This paper provides a thorough understanding of different magnetic refrigeration technologies using a variety of models to evaluate the coefficient of performance (COP) and specific cooling capacity outputs. Accordingly, magnetic refrigeration models are divided into four categories: rotating, reciprocating, C-shaped magnetic refrigeration, and active magnetic regenerator. The working principles of these models were described, and their outputs were extracted and compared. Furthermore, the influence of the magnetocaloric effect, the magnetization area, and the thermodynamic processes and cycles on the efficiency of magnetic refrigeration was investigated and discussed to achieve a maximum cooling capacity. The classes of magnetocaloric magnetic materials were summarized from previous studies and their potential magnetic characteristics are emphasized. The essential characteristics of magnetic refrigeration systems are highlighted to determine the significant advantages, difficulties, drawbacks, and feasibility analyses of these systems. Moreover, a cost analysis was provided in order to judge the feasibility of these systems for commercial use.
•A concept of a cascade LiBr/H2O absorption refrigeration/transcritical CO2 process is proposed.•The proposed system is driven by low-grade waste heat.•The low-grade waste heat is utilized in a ...cascade approach to produce electricity.•The proposed system is designed following two optimization strategies.•Performance and parameters are analyzed and compared.
In this paper, a cascade LiBr/H2O absorption refrigeration/transcritical CO2 process is proposed to recover 90–150 °C low-grade waste heat. The proposed system consists of two subsystems: LiBr/H2O cycle and transcritical CO2 cycle. The low-grade waste heat is utilized by LiBr/H2O cycle and transcritical CO2 cycle in a cascade approach. Two optimization strategies, following efficiency of performance (FCP) and following net electricity generation (FNG), are proposed to design the cascade LiBr/H2O absorption refrigeration/transcritical CO2 process. A series processes on various refrigeration temperature (i.e., 2 °C, 3 °C, 4 °C, 5 °C, 7 °C, and 10 °C) are designed following the two optimization strategies. Key parameters in terms of refrigeration temperature, segment temperature, and high pressure are analyzed. In addition, the performance of the designed processed are compared based on the simulation results. Results show that the proposed system shows a better performance at the lower refrigeration temperature of the LiBr/H2O cycle. The high pressure under FCP is larger than that under FNG. The investment and profit of the optimal design under FCP are both more than that under FNG. This work provides a potential way to generate electricity using low-grade waste heat.
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