Recent advances in vapor compression cycle technologies

To improve energy efficiency in industry, low-grade heat recovery technologies have been advanced continuously. This chapter aims to provide a basic understanding of state-of-the-art technologies for low-grade heat recovery and utilization in industry, which are developed based on the concept of thermodynamic cycles. The technologies include adsorption, absorption, liquid desiccant, organic Rankine cycles (ORC), and Kalina cycles. The definition of low-grade heat sources, the working principle, recent advances in research and development (R&D), and commercial applications of the technologies (if any) will be discussed, followed by concluding remarks on advantages and disadvantages, future outlook, barriers, and opportunities.

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“…As vapor compression systems are conventional technology, they are not further discussed in this chapter. More details are available in [11].…”

Section: Vapor Compressionmentioning

confidence: 99%

State-of-the-Art Technologies on Low-Grade Heat Recovery and Utilization in Industry

Ling‐Chin

Bao

et al. 2019

Energy Conversion - Current Technologies and Future Trends

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“…Yu et al [63] proposed a new ejector enhanced vapour compression refrigeration cycle ( Figure 7) operating with refrigerant R32, which improves the COPh and volumetric capacity by more than [8.8, 9.3]% and [13.6, 9.7]%, respectively. Finally, the use of an internal heat exchanger (IHX) is not recommended for R32 because it reduces the COPc and increases the discharge temperature, even though this component can enlarge the energy efficiency for some of its mixtures, as with R407C or R410A [64].…”

Section: Performance and Discharge Temperature Concern Of Pure R32mentioning

confidence: 99%

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

Mota-Babiloni

Navarro-Esbrí

Makhnatch

et al. 2017

Renewable and Sustainable Energy Reviews

111

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Because air conditioning and heat pump systems contribute greatly to greenhouse gas emissions, equipment with both lower global warming potential (GWP) working fluids and a higher level of performance should be used. R32 (difluoromethane) has been proposed to substitute R410A, particularly in residential air conditioning (RAC) systems. This study collected the most relevant and recent researches into R32 as a refrigerant so as to assess its viability in RAC systems in both Europe and the USA, as compared to R410A and other lower GWP RAC alternatives.The R32 value of GWP is 677, which is below the F-gas regulation limit in RAC equipment (750). According to ASHRAE standard 34, R32 is less flammable than hydrocarbons, and the amount of charge permitted for R32 is above the necessary level in RAC equipment. It can be concluded that R32 has significantly good heat transfer characteristics and a level of performance that make it acceptable at low condensing temperatures, thereby avoiding overly high compressor discharge temperatures. Its performance is very similar to that of R410A across the entire operating range, and it is therefore believed that R32 will be utilized in RAC systems in the remaining countries that prioritize lower GWP fluids but are less strict in their security regulations.To replace R410A under extreme conditions, some system modifications can be conducted, or R32 mixtures with hydrofluoroolefins (HFOs) can be used. Such mixtures achieve a lower performance than R32, but are acceptable replacements when considering their lower GWP compared to that of R32, and similar level of flammability. Finally, other (R32-based) alternative mixtures have also been developed and their behaviours studied under a wide range of operating conditions.

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“…For minimum power consumption in industrial applications, gases should ideally be cooled at the same time they are being compressed [ 1 ], maintaining their initial temperature as constant during the whole process [ 2 ]. The increase in power consumption caused by compressing a gas that is progressively getting hotter, with large mass flows and long operating hours can be economically unsustainable [ 3 , 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Step by Step Derivation of the Optimum Multistage Compression Ratio and an Application Case

López‐Paniagua

Rodríguez-Martín

Orgaz

et al. 2020

Entropy

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The optimum pressure ratio for the stages of a multistage compression process is calculated with a well known formula that assigns an equal ratio for all stages, based on the hypotheses that all isentropic efficiencies are also equal. Although the derivation of this formula for two stages is relatively easy to find, it is more difficult to find for any number of stages, and the examples that are found in the literature employ complex mathematical methods. The case when the stages have different isentropic efficiencies is only treated numerically. Here, a step by step derivation of the general formula and of the formula for different stage efficiencies are carried out using Lagrange multipliers. A main objective has been to maintain the engineering considerations explicitly, so that the hypotheses and reasoning are clear throughout, and will enable the readers to generalise or adapt the methodology to specific problems. As the actual design of multistage compression processes frequently meet engineering restrictions, a practical example has been developed where the previous formulae have been applied to the design of a multistage compression plant with reciprocating compressors. Special attention has been put into engineering considerations.

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Recent advances in vapor compression cycle technologies

Cited by 138 publications

References 45 publications

State-of-the-Art Technologies on Low-Grade Heat Recovery and Utilization in Industry

State-of-the-Art Technologies on Low-Grade Heat Recovery and Utilization in Industry

Refrigerant R32 as lower GWP working fluid in residential air conditioning systems in Europe and the USA

Step by Step Derivation of the Optimum Multistage Compression Ratio and an Application Case

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