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Abstract

Thermodynamic analysis of car air cooler is presented in this paper. Typical refrigerator cycles are studied. The first: with uncontrolled orifice and non controlled compressor and the second one with the thermostatic controlled expansion valve and externally controlled compressor. The influence of the refrigerant decrease and the change of the air temperature which gets to exchangers on the refrigeration efficiency of the system; was analysed. Also, its effectiveness and the power required to drive the compressor were investigated. The impact of improper refrigerant charge on the performance of air conditioning systems was also checked.
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Abstract

As a kind of mass transfer process as well as the basis of separating and purifying mixtures, interfacial adsorption has been widely applied to fields like chemical industry, medical industry and purification engineering in recent years. Influencing factors of interfacial adsorption, in addition to the traditional temperature, intensity of pressure, amount of substance and concentration, also include external fields, such as magnetic field, electric field and electromagnetic field, etc. Starting from the point of thermodynamics and taking the Gibbs adsorption as the model, the combination of energy axiom and the first law of thermodynamics was applied to boundary phase, and thus the theoretical expression for the volume of interface absorption under electric field as well as the mathematical relationship between surface tension and electric field intensity was obtained. In addition, according to the obtained theoretical expression, the volume of interface absorption of ethanol solution under different electric field intensities and concentrations was calculated. Moreover, the mechanism of interfacial adsorption was described from the perspective of thermodynamics and the influence of electric field on interfacial adsorption was explained reasonably, aiming to further discuss the influence of thermodynamic mechanism of interfacial adsorption on purifying air-conditioning engineering under intensification of electric field.
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Abstract

Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50°C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25°C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.
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Abstract

According to The European Commission’s regulation numbers 842/2006 and 517/2014, refrigerants whose Global Warming Potential ratio is more than 150, have been prohibited in mobile air conditioning (MAC) since January 2017. Therefore, the commonly used R-134 gas has been banned. The search for a new refrigerant, which grants all the required criteria, has begun. In accordance with new European standards, the gas should have environmentally friendly properties and should not be noxious to human life while operating. In this paper, two alternative substances, which can substitute the banned R134a, have been compared. This is synthetic R1234yf, which belongs to the HFO group, and carbon dioxide, which exists in the natural environment. The chemical build, physical and thermodynamic properties have been described. Scientific articles, which present and compare the technical results of testing both refrigerants, have been discussed. Comparison results, tools used and research methodology have been described in these articles. Alternative gases have been analyzed for their environmental impact and have been checked on the toxic, flammable, impact on ozone depletion and global warming. The threats to human life due to the use of the new refrigerants have been reviewed. The thesis also comprises an economical comparison between the two gases. A short review and conclusions have been presented at the end of the article.
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Abstract

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics. Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points. Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.
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Abstract

The flat horizontal polymer loop thermosyphon with flexible transport lines is suggested and tested. The thermosyphon envelope consists of a polyamide composite with carbon based high thermal conductive micro-, nanofilaments and nanoparticles to increase its effective thermal conductivity up to 11 W/(m°C). Rectangular capillary mini grooves inside the evaporator and condenser of thermosyphon are used as a mean of heat transfer enhancement. The tested working fluid is R600. Thermosyphon evaporator and condenser are similar in design, have a long service life. In this paper three different methods (transient, quasi-stationary, and stationary) have been used to determine the thermophysical properties of polymer composites used as an envelope of thermosyphon, which make it possible to design a wide range of new heat transfer equipment. The results obtained contribute to establish the viability of using polymer thermosyphons for ground heat sinks (solar energy storage), gas-liquid heat exchanger applications involving seawater and other corrosive fluids, efficient cooling of superconductive magnets impregnated with epoxy/carbon composites to prevent wire movement, enhance stability, and diminish heat generation.
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Abstract

This paper presents the parameters of the reference oxy combustion block operating with supercritical steam parameters, equipped with an air separation unit and a carbon dioxide capture and compression installation. The possibility to recover the heat in the analyzed power plant is discussed. The decision variables and the thermodynamic functions for the optimization algorithm were identified. The principles of operation of genetic algorithm and methodology of conducted calculations are presented. The sensitivity analysis was performed for the best solutions to determine the effects of the selected variables on the power and efficiency of the unit. Optimization of the heat recovery from the air separation unit, flue gas condition and CO2 capture and compression installation using genetic algorithm was designed to replace the low-pressure section of the regenerative water heaters of steam cycle in analyzed unit. The result was to increase the power and efficiency of the entire power plant.
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