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International Journal of Refrigeration
IPC Science and Technology Press
International Journal of Refrigeration

IPC Science and Technology Press

0140-7007

International Journal of Refrigeration/Journal International Journal of RefrigerationSCIEI
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    Analysis of the novel multi-vane Revolving Vane compressor – Investigation of vane chattering phenomenon through instantaneous working chamber pressure measurements

    Choo W.C.Ooi K.T.
    12页
    查看更多>>摘要：This paper presents the analysis of the vane chattering phenomenon through measurements of the instantaneous working chamber pressure of the multi-vane Revolving Vane (RV) compressor. The paper presents the prototype design, measurement setup, and processing of the recorded data to support the phenomenon. The analysis confirmed that the vane chattering was originated by the two free vanes which were detached and re-collided with the cylinder inner wall repeatedly during the course of compressor operation in the 60°–135° and 190°–255° angular position regions, respectively. Reasons of vane chattering have been hypothesized through the data collected and further verified with the mathematical model describing the dynamic behaviour of the free vanes.
      原文链接:
    • NSTL
    • Elsevier

    Mathematical modeling and parametric study of the lima?on rotary compressor

    Lu K.Sultan I.A.Phung T.H.
    13页
    查看更多>>摘要：In this paper, a class of rotary positive displacement compressors which is known as the lima?on compressor is introduced. The main feature of such a compressor is that profiles of its housing and rotor and the motion of its rotor are developed from a mathematical curve called the lima?on of Pascal. A mathematical model of the lima?on compressor, which incorporates the mass flow of the working fluid, the leakage loss, the dynamic response of the discharge valve, as well as the thermodynamic behaviors, is formulated, and the simulation of such a model has been performed to study the operational characteristics of the lima?on compressor. A parametric analysis is also conducted to investigate the effects of various parameters on the compressor performance. Based on the results, it is found that the machine performance deteriorates as the operating speed increases despite an initial rise in the volumetric efficiency. Additionally, the isentropic efficiency appears insensitive to the change of the pressure ratio, whereas a negative effect on the volumetric efficiency is noticed when the pressure ratio is increased. The effect of the valve diameter on the over-compression loss has also been studied, and the result indicates that a smaller valve diameter leads to a higher level of fluid over-compression.
      原文链接:
    • NSTL
    • Elsevier

    Analysis of hybrid compression absorption refrigeration using low-GWP HFC or HFO/ionic liquid working pairs

    Asensio-Delgado J.M.Asensio-Delgado S.Zarca G.Urtiaga A....
    10页
    查看更多>>摘要：Absorption refrigeration systems (ARS) are the leading alternative for reducing the electricity costs associated with compression refrigeration systems. However, classical pairs based on NH3/H2O and H2O/LiBr have drawbacks that limit their practical application. In this work, we analyze 16 pairs of refrigerant gases and ionic liquid sorbents based on two low global warming potential (GWP) hydrofluorocarbons (HFCs), R32 and R134a, and two novel hydrofluoroolefins (HFOs), R1234ze(E) and R1234yf, using the low-viscosity ionic liquids [C2mim][BF4], [C2mim][OTf], [C2mim][SCN], and [C2mim][Tf2N]. We provide new data and modeling of the vapor-liquid equilibria of R1234ze(E) with [C2mim][OTf], [C2mim][SCN] and [C2mim][Tf2N]. ARS performance in single-effect (SE-ARS) and compression-assisted absorption refrigeration (CA-ARS), in terms of coefficient of performance (COP, ECOP), solution circulation factor (f), and the thermal and electrical contribution to the total COP, is evaluated through energy and exergy analyses. The results showed that CA-ARS performs better even at lower generator temperatures. In addition, HFCs returned a better performance than HFOs because of their higher solubility in ILs. The working pair R32/[C2mim][Tf2N] gave the best results, COP = 0.74 and f = 5.4 at 328 K in the desorber, and a maximum ECOP of 0.41 at 318 K. Furthermore, the HFO R1234ze(E), with a lower working pressure and negligible GWP, is also a promising option for CA-ARS. In conclusion, we consider that ARS with the HFC or HFO/IL pairs examined in this study shows outstanding potential as a more energy efficient system compared to compression systems, when an inexpensive energy source is available.
      原文链接:
    • NSTL
    • Elsevier

    A novel defrosting initiating strategy for automotive air conditioner heat pumps based on frost thickness growth prediction

    Chen J.Wu J.He J.Guo Z....
    11页
    查看更多>>摘要：Automotive air conditioning heat pump systems draw increasing attention as an alternative to conventional electric heaters. Once the air temperature falls below the freezing point, frost begins to form on the surface of the evaporator. The accurate defrost strategies could avoid heat exchange efficiency reduction and prevent heating capacity from decaying, which are the main factors affecting the energy efficiency of electric vehicle heat pump systems. The frost characteristic on micro-channel heat exchanger of the electric vehicle heat pump system is tested, and a novel defrosting strategy which is based on the dimensionless analysis method is introduced too. Conclusions could be drawn as following: a correlation that considers the effects of ambient parameters and structural parameters has been developed to predict the frost thickness on fins with dimensionless analyses. Based on this correlation, the relative error and the RMS error between the experimental data and the predicted value are 8.44% and 12.54%, respectively; the effective blockage ratio (EBR), a parameter that accurately reflects the blockage ratio and directly linked to the system operation state, is first proposed. Through the analysis between the EBR and system heating capacity, it can be concluded that the optimal defrosting start-point is identified as the EBR reaches 30%. With this method, the defrosting start-time can be found accurately and effectively to avoid unnecessary defrost cycles, thus leading to a highly efficient operation and low energy consumption for the electric vehicle heat pump system.
      原文链接:
    • NSTL
    • Elsevier

    Performance assessment of R1234ze(E) as a low GWP substitute to R410A in fin-and-tube heat exchangers

    Saleem S.Bradshaw C.R.Bach C.K.
    12页
    查看更多>>摘要：Several energy efficiency regulations worldwide are forcing air conditioning and heat pump manufacturers to replace the halogenated refrigerants currently used in these systems, such as R410A, with more climate friendly alternatives that have a lower Global Warming Potential (GWP). This study explores how the performance of R1234ze(E) compares for an R410A based fin-and-tube evaporator coil. A total of 36 experiments were completed for both refrigerants, by means of a high-fidelity experimental facility, to validate a segment-by-segment heat exchanger model. For R410A, the mean absolute percent error between the experimental and simulated capacity was found to be 0.9%, and it was 1.4% for R1234ze(E). Simulations were then carried out, using the model, with R1234ze(E), where the fin density and refrigerant circuitry of the original heat exchanger were altered independently. By increasing the fin density from 15 to 20 fins per inch (FPI), the capacity increased by 4.9%, and refrigerant side pressure drop decreased by 4.5%. For the refrigerant circuitry optimizations, a maximum increase in capacity of 5.6% was observed when compared to the baseline, but at the expense of 7.5 times higher pressure drop. Alternatively, a separate circuitry resulted in a 38% pressure drop reduction and 2.5% reduction in capacity. The results demonstrated the relative sensitivity of capacity and refrigerant side pressure drop for R1234ze(E) on only two heat exchanger geometrical parameters. This sensitivity suggests potential for additional optimizations to heat exchanger designs for low-GWP refrigerants by performing further parametric analysis on heat exchanger geometry.
      原文链接:
    • NSTL
    • Elsevier

    Experimental investigation of dedicated desiccant wheel outdoor air cooling systems for nearly zero energy buildings

    Chen L.Chu Y.Deng W.
    13页
    查看更多>>摘要：In high-temperature and high-humidity environments, a large amount of energy is consumed to cool and dehumidify outdoor air by dedicated outdoor air systems in nearly zero energy buildings. Desiccant wheels have the advantages of large moisture removal capacities and continuous regeneration. However, the application of desiccant wheels in nearly zero energy buildings is limited by their large regeneration heat capacity and high temperature after dehumidification. A dedicated desiccant wheel outdoor air cooling system is thus proposed. An experimental setup is built and used to test the performances of three modes for dedicated desiccant wheel outdoor air cooling systems. The results show that mode Ⅰ (wet membrane humidifier downstream evaporation section of heat pipe heat exchanger) has a higher performance coefficient and higher exergy efficiency compared to other modes. The thermodynamic and exergy performances of the proposed mode Ⅰ system are determined. The results show that the thermodynamic coefficient decreases from 1.3 to 0.52 and the exergy efficiency decreases from 0.76 to 0.18 when the regeneration temperature increases from 60°C to 110°C.
      原文链接:
    • NSTL
    • Elsevier

    Solubility measurements of refrigerants in polyolesters lubricants at temperature from 323.K to 383.K

    Brocus J.Valtz A.Coquelet C.De Carlan F....
    15页
    查看更多>>摘要：In refrigeration systems and heat pumps, lubricant selection is important to avoid issues that can lead to a breakdown of the compressor and the entire system. Daniel plots are a great tool to make the selection. Half of the graph is the solubility of refrigerant in lubricating oil. Isothermal vapor-liquid equilibrium (VLE) data are measured for five refrigerants in four oils. Refrigerants include HFC-32 (dichlorofluoromethane), HFC-134a (1,1,1,2-tetrafluoroethane), HFO-1234yf (2,3,3,3-tetrafluoropropene), HFO-1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) and HCFO-1233zd(E) (trans-1?chloro-3,3,3-trifluoroprop-1-ene) in four oils named POE 80, SE 55, SE 170 and SE 220, based on their viscosity grade. The experimental technique used is based on static synthetic methods. All of the data are correlated with the cubic equation of state developed by Yokozeki.
      原文链接:
    • NSTL
    • Elsevier

    Solidification performance enhancement of encapsulated ice storage system by fins and copper foam

    Wang H.Xiang H.Lou X.
    11页
    查看更多>>摘要：It is critical for the encapsulated ice storage system to maintain high cooling capacity within permissible time. In this paper, the strengthening effects of metal foam and fins on ice storage spheres are numerically studied comprehensively. The variations of the temperature field, ice front evolution, solidification fraction, total solidification time and the cold storage capacity are analyzed under four different strengthening configurations (plain, fins, metal foam and metal foam composite fins). The optimum porosity is obtained after the comparison of four comprehensive criteria about the input-output performance. Finally, the dimensionless parameters of the metal foam ice storage sphere are analyzed. The results demonstrate that the temperature distribution in the metal foam ice storage sphere is more uniform, and the solidification rate is faster due to coupled effects of thermal conduction enhancement and the suppression of the natural convection. Metal foam composite fins can remarkably save 83.5% of the solidification time and enhance the solidification rate by 6.1 times compared with the non-enhancement case. Dimensional analysis of the results is presented as the solidification fractions versus an appropriate combination of the porosity, Fourier, and Stefan numbers. Compared with the previous non-metal foam prediction formula, the formula reported in this research is more accurate. The prediction accuracy can improve by 20%.
      原文链接:
    • NSTL
    • Elsevier

    Thermoeconomic and thermoenvironmental analysis of the chilled water system in a shopping mall

    Abreu R.P.Correia V.H.L.Lourenco A.B.Marques A.D.S....
    8页
    查看更多>>摘要：This is the first study to apply a combination of two thermoeconomic approaches (UFS and H&S) with Life Cycle Assessment (LCA) to a chilled water system installed in a shopping mall. The objective is to obtain monetary and environmental costs for the thermal energy stored by developing both thermoeconomic and thermoenvironmental assessments. The thermoeconomic study determined internal flows, defined inputs and products, and described the productive structure to obtain exergy and monetary costs. The LCA methodology quantified the greenhouse gas emissions associated with equipment operation and energy flows. The results indicated efficient thermoeconomic behavior for the heat exchangers. The monetary and environmental costs of chilled water are, respectively, US$ 0.2267/MJ and 0.8186 kg CO2-eq/MJ.
      原文链接:
    • NSTL
    • Elsevier

    Experimental investigation of a new combined refrigeration system

    Goudarzi K.Jalil E.Mousavi M.R.
    8页
    查看更多>>摘要：In this paper, experimental study has been performed to investigate the performance of a new combined cooling system (CCS) included indirect evaporative cooler and 4-bed solar adsorption cooling system. Solar adsorption cooling system acted as pre-cooling for the CCS. in this study, two mass flow rates passing from evaporator of 0.1 and 0.15 kg s?1, and also three volumetric air flow rates passing from indirect evaporative cooler of 700, 850 and 1000 m3 h?1, were investigated. Results were shown that, the highest average efficiency was 104% and obtained for minimum of mass flow passing from solar adsorption cooling system (0.1 kg s?1) and minimum of volumetric air passing from indirect evaporative coolind system (700 m3 h?1). Also, the average efficiency of combined cooling was in the range of 84–104%.
      原文链接:
    • NSTL
    • Elsevier