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Many efforts have been made to reduce the energy consumption of centralized systems by employing advanced refrigeration systems to increase their energy efficiency. Some practical examples include reduced head pressure and mechanical subcooling. This chapter deals with technical and thermodynamic aspects of advanced versions of conventional refrigeration systems, but unconventional systems as well as innovative refrigeration methods and systems. Thermodynamic analyses of advanced refrigeration systems are presented through energy and exergy analyses, and exergetic and exergetic coefficient of performances (COPs). For some industrial applications which require moderately low temperatures (with a large temperature and pressure difference), single vapor‐compression refrigeration cycles become impractical. One of the solutions for such cases is to perform the refrigeration in two or more stages which operate in series. These refrigeration cycles are called cascade refrigeration cycles. The most important advantage of these cascade systems is that refrigerants can be chosen with the appropriate properties, avoiding large dimensions for system components.

This chapter contains sections titled: Introduction Multistage Refrigeration Cycles Cascade Refrigeration Systems Liquefaction of Gases Steam Jet Refrigeration Systems Thermoelectric Refrigeration Thermoacoustic Refrigeration Metal Hydride Refrigeration Systems Solar Refrigeration Magnetic Refrigeration Supermarket Refrigeration Concluding Remarks Nomenclature Study Problems References

In this work the thermodynamic performance of a transcritical R744 booster supermarket refrigeration system equipped with R290 dedicated mechanical subcooling (DMS) was exhaustively investigated with the aid of the advanced exergy analysis. The outcomes obtained suggested that improvement priority needs to be addressed to the manufacturing of more efficient high-stage (HS) compressors, followed by the enhancement of the gas cooler/condenser (GC), of the medium-temperature (MT) evaporators, of the R290 compressor, and of the low-temperature (LT) evaporators. These conclusions were different from those drawn by the application of the conventional exergy assessment. Additionally, it was found that GC can be enhanced mainly by reducing the irreversibilities owing to the simultaneous interaction among the components. The R290 compressor would also have significantly benefitted from the adoption of such measures, as half of its avoidable irreversibilities were exogenous. Unlike the aforementioned components, all the evaporators were improvable uniquely by decreasing their temperature difference. Finally, the approach temperature of GC and the outdoor temperature were found to have a noteworthy impact on the avoidable irreversibilities of the investigated solution.

With the increase of spindle speed, heat generation becomes the crucial problem of high-speed motorized spindle. A new cooling system for motorized spindle is proposed based on the principles of thermoelectric refrigeration and fast heat conduction. The main strategy of the proposed thermoelectric-based cooling system (TECS) is using the thermoelectric cooler (TEC) to cool the spindle through a heat conduction sleeve (HCS). The TEC is designed according to the heat generation of motorized spindle. The cooling capacity generated by the TEC is controlled by electric current passing through the TEC according to the temperature rise of HCS. The HCS is designed to distribute the cold quickly and is installed around the spindle sleeve working as cooling medium. The simulation results show that the cooling effect of the proposed TECS is better than water-cooling system. It is meaningful to improve the accuracy of motorized spindle.

The growing demand for current and future projects lacks materials development and their manufacturing process, mainly when they need to be used in inert applications, where no physical or chemical reaction can interact with the elements around them. In this context, ceramic materials have stood out in applications that demand high resistance to temperature and wear, such as engine components and in situations where greater stability and chemical compatibility are required, such as prostheses and medical components. However, the manufacture of ceramic components is expensive and slow, given that the traditional manufacturing procedure for ceramic components is based on sintering. This process limits productivity and does not provide the final component with the high dimensional and shape quality required in more specific applications. However, there is still a lack of studies on the large-scale manufacturing processes of these products, mainly related to their grinding. Therefore, it is crucial to study the best ways of processing materials that will soon be essential to the mechanical, electronic, and biological industries. Furthermore, studies about advanced ceramics have become increasingly indispensable, based on factors such as high added values due to the difficulty of manufacturing combined with the high environmental impact caused by this process. However, advanced ceramics are materials with difficult to machine because of their high hardness and fragility properties, becoming required manufacturing processes more complex, such as grinding. Therefore, this paper explored several conditions applied to advanced ceramic, approaching the main variables used by worldwide industries, being: surface roughness (Ra), roundness error, diametral wheel wear, G-ratio, grinding power, and analysis costs process. The grinding process used in the research was of kind plunge combined with a diamond wheel applied to four different feed rates: 0.25, 0.50, 0.75, and 1.00 mm/min, in which two systems by application of cutting fluid in the process were also used: flood and MQL lubri-refrigeration techniques, with a flow rate of 15 l/min and 100 ml/h, respectively. The results indicated that the final conditions were affected by the increase in feed rate for both situations. Nonetheless, they were superior to those when the flood technique was used. However, the cost analysis process indicated that the drastic reduction of the amount of cutting fluid applied by the MQL provides better economic conditions when compared to the flood application technique, becoming this technique viable for industry application.

This paper aims to evaluate the feasibility and performances of a novel hybrid solar–gas system, which provides electric power and cooling. By using Ebsilon (V15.0) software, the operation, advanced exergic and economic analyses of this hybrid system are conducted. The analysis results show that the total electric power and energy efficiency of the hybrid system are 96.0 MW and 45.8%. The solar energy system contributes an electric power of 9.0 MW. The maximum cooling load is 69.66 MW. The exergic loss and exergic efficiency of the whole hybrid system are 119.1 MW and 44.6%. The combustion chamber (CC) has the maximum exergic loss (56.5 MW). The exergic loss and exergic efficiency of the solar direct steam generator (SDSG) are 28.5 MW and 36.2%. For the air compressor (AC), CC, heat recovery steam generator (HRSG) and refrigeration system (CSS), a considerable part of the exergic loss is exogenous. The avoidable exergic loss of the CC is 11.69 MW. For the SDSG, there is almost no avoidable exergic loss. Economic analysis shows that for the hybrid system, the levelized cost of energy is 0.08125 USD/kWh, and the dynamic recycling cycle is 5.8 years, revealing certain economic feasibility. The results of this paper will contribute to the future research and development of solar–gas hybrid utilization technology to a certain extent.

Abstract The centerless grinding process is a fast and efficient process for precision batch and mass production grinding. This process employs wide wheels which allow substantial removal rates, and another additional advantage is that centers are not required as in center grinding. Wide wheels yield to lower wheel wear and higher accuracy for long periods, particularly when using in-process gauging. Many materials and parts of various shapes and sizes are produced by the centerless grinding, in particular, for bearing and automotive industries. In grinding process, the application of metal working fluid (MWF) in order to avoid thermal damages and excessive form deviation are indispensable. In this regard, this work aims to contribute to optimization of machining process through-feed by the study of centerless grinding process under the application of the optimized lubri-cooling technique by a novel multitubular nozzle for various cutting conditions. The multitubular nozzle was employed with emulsion (ME) and compressed air simultaneously (ME + CA) and with conventional nozzle (CN) application for a stock material removal (SMR) of 0.10 and 0.03 mm. All techniques were tested for three different flow rates: 10, 20, and 40 L/min. Surface roughness of the ground surface, roundness deviation, and SEM images of roundness deviation were analyzed. As a result, the ME + CA optimized application produced lower results than CN nozzles in general and the increase of surface roughness values is also produced by higher feed rate values which results in thicker chips in grinding process.

After the recent renewed interest in CO2 as the refrigerant (R744) for the food retail industry, many researchers have focused on the performance enhancement of the basic transcritical R744 supermarket refrigeration unit in warm climates. This task is generally fulfilled with the aid of energy-based methods. However, the implementation of an advanced exergy analysis is mandatory to properly evaluate the best strategies needing to be implemented to achieve the greatest thermodynamic performance improvements. Such an assessment, in fact, is widely recognized as the most powerful thermodynamic tool for this purpose. In this work, the advanced exergy analysis was applied to a conventional R744 booster supermarket refrigerating system at the outdoor temperature of 40 °C. The results obtained suggested the adoption of a more sophisticated layout, i.e., the one outfitted with the multi-ejector block. It was found that the multi-ejector supported CO2 system can reduce the total exergy destruction rate by about 39% in comparison with the conventional booster unit. Additionally, the total avoidable exergy destruction rate was decreased from 67.60 to 45.57 kW as well as the total unavoidable exergy destruction rate was brought from 42.67 down to 21.91 kW.

A comprehensive techno-economic evaluation is evaluated based on an innovative compound ejector-heat pump system with PV/T (photovoltaic thermal) waste heat-driven. The aim of the system is simultaneous data centre cooling and waste heat recovery for district heating to reduce residential greenhouse gas emissions. The new system avoids the ejector pump by combining PV/T waste heat with an evaporative-condenser as an ejector driving force, considering several low global warming potential alternatives to R134a. The simulation indicates that the proposed system presents a remarkable difference in all investigated refrigerants’ overall system coefficient of performance (COP). Particularly, R515B presents the highest increase in COP, 54% and 49% in cooling and heating modes, respectively. It also provides the highest electricity consumption reduction, 84.1 MWh yearly. Moreover, the system improves the data centre power usage effectiveness (PUE) index from 10 to 19%. In financial terms, the shortest payback period (6.3 years) is obtained with R515B, followed by R515A and R1234ze(E).

For many of these materials, the key properties of interest are highly sensitive to crystallographic orientation and the details of the microstructure. [...]processing conditions can be nearly as important as the sample chemistry. [...]magnetocaloric cooling systems can replace the existing traditional vapor-compression refrigeration technology and eliminate their associated complications, such as the need for environmentally unfriendly and hazardous chemicals. [...]an article by Baker et al. describes \"Cold Spray Deposition of Thermoelectric Materials.\"