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  • 1. Andersson, K.
    et al.
    Granryd, Eric
    KTH.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Water to water heat pump with minimum charge of propane2018In: Refrigeration Science and Technology, International Institute of Refrigeration, 2018, p. 725-732Conference paper (Refereed)
    Abstract [en]

    This paper describes the technology for an environmentally friendly ground source heat pump for a single family home, characterized by using pure water as coolant and propane as refrigerant. The objective was to build a test system, operating under realistic conditions, using less than 150 g of propane, providing at least 5 kW heating capacity with reasonable efficiency and without freezing the coolant water. The borehole heat exchanger was of coaxial type, providing about half the thermal resistance compared to a standard U-tube collector (Acuña 2010). The evaporator and condenser where asymmetrical plate heat exchangers with small channel height (< 1 mm) on the refrigerant side. They were developed and manufactured exclusively for this project with a new type of press pattern, including a special, small volume sub-cooling section at the end of the condenser. A DC-motor scroll compressor for AC in electric vehicles was used, characterized by small internal volumes, small oil charge and wide capacity range (800-9000 rpm). A PAG-type oil was used, which however seemed to cause some problems with heat transfer and pressure drop in the evaporator. The system also included a specially built mini channel liquid/suction line heat exchanger and a standard thermostatic expansion valve. The paper presents test results for a heating capacity range of 2-10 kW. The performance was reasonable in this range with a charge of 100 g of propane (-1<T2<5°C, 30<T1<55°C). The charge that is required is determined at the lowest capacities, at low compressor speed and high evaporating pressures. A lower charge is beneficial at higher capacities.

  • 2.
    Björk, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Acuña, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Mogensen, Palne
    Nowacki, Jan-Erik
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Weber, Kenneth
    Bergvärme på djupet: Boken för dig som vill veta mer om bergvärmepumpar2013 (ed. 100)Book (Other (popular science, discussion, etc.))
    Abstract [sv]

    I den här boken får du lära dig mer om bergvärmepumpar. Hur fungerar en värmepump? Hur gör man en lönsamhetskalkyl? Hur upphandlar man? Kan man trimma sitt system? Dessutom: lär dig mer om radiatorsystemet, berget och kollektorn.

  • 3.
    Fernando, W. Primal D.
    et al.
    KTH, Superseded Departments, Energy Technology.
    Han, Han
    KTH, Superseded Departments, Energy Technology.
    Palm, Björn
    KTH, Superseded Departments, Energy Technology.
    Granryd, Eric
    KTH, Superseded Departments, Energy Technology.
    Lundqvist, Per
    KTH, Superseded Departments, Energy Technology.
    The Solubility of Propane (R290) with Commonly Used Compressor Lubrication Oils2003In: Compressors and Their Systems, 2003, Vol. 4, p. 157-166Conference paper (Refereed)
    Abstract [en]

    An ongoing project called "Charge minimisation of a small capacity heat pump" is aimed to minimise the refrigerant charge in heat pumps, refrigeration and air-conditioning systems. The experimental heat pump was run with propane as refrigerant and the designed heat capacity (condenser capacity) was over 5kW. Tests were done to investigate the refrigerant charge distribution in different sections of the heat pump, while it was running. The experiments done so far have shown that the amount of refrigerant in the compressor is higher than expected.

    This paper presents the measured refrigerant masses in a hermetic scroll compressor together in suction line and the calculated refrigerant mass dissolved in the compressor lubrication oil at different evaporation temperatures. Finally, solubility tests of propane with different lubricating oils are presented. The tests show that the propane is more soluble in POE than PAG oils.

  • 4.
    Fernando, W. Primal D.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Ameel, Tim
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    A Minichannel Aluminium Tube Heat Exchanger - Part 1: Evaluation of Single-Phase Heat Transfer Coefficients by the Wilson Plot Method2008In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, no 4, p. 669-680Article in journal (Refereed)
    Abstract [en]

    A prototype liquid-to-refrigerant heat exchanger was developed with the aim of minimizing the refrigerant charge in small systems. To allow correct calculation of the refrigerant side heat transfer, the heat exchanger was first tested for liquid-to-liquid (water-to-water) operation in order to determine the single-phase heat transfer performance. These single-phase tests are reported in this paper. The heat exchanger was made from extruded multiport aluminium tubes and was designed similar to a shell-and-tube heat exchanger. The heat transfer areas of the shell-side and tube-side were approximately 0.82 m(2) and 0.78 m(2), respectively. There were six rectangular-shaped parallel channels in a tube. The hydraulic diameter of the tube-side was 1.42 mm and of the shell-side 3.62 mm. Tests were conducted with varying water flow rates, temperature levels and heat fluxes on both the tube and shell sides at Reynolds numbers of approximately 170-6000 on the tube-side and 1000-5000 on the shell-side, respectively. The Wilson plot method was employed to investigate the heat transfer on both the shell and tube sides. In the Reynolds number range of 2300-6000, it was found that the Nusselt numbers agreed with those predicted by the Gnielinski correlation within +/- 5% accuracy. In the Reynolds number range of 170-1200 the Nusselt numbers gradually increased from 2.1 to 3.7. None of the previously reported correlations for laminar flow predicted the Nusselt numbers well in this range. The shell-side Nusselt numbers were found to be considerably higher than those predicted by correlations from the literature.

  • 5.
    Fernando, W. Primal D.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Ameel, Tim
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    A minichannel aluminium tube heat exchanger - Part II: Evaporator Performance with Propane2008In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, no 4, p. 681-695Article in journal (Refereed)
    Abstract [en]

    This paper presents heat transfer data for a multiport minichannel heat exchanger vertically mounted as an evaporator in a test-rig simulating a small water-to-water heat pump. The multiport minichannel heat exchanger was designed similar to a shell-and-tube type heat exchanger, with a six-channel tube of 1.42 mm hydraulic diameter, a tube-side heat transfer area of 0.777 m(2) and a shell-side heat transfer area of 0.815 m(2). Refrigerant propane with a desired vapour quality flowed upward through the tubes and exited with a desired superheat of 1-4 K. A temperature-controlled glycol solution that flowed downward on the shell-side supplied the heat for the evaporation of the propane. The heat transfer rate between the glycol solution and propane was controlled by varying the evaporation temperature and propane mass flow rate while the glycol flow rate was fixed (18.50 l min(-1)). Tests were conducted for a range of evaporation temperatures from -15 to +10 degrees C, heat flux from 2000 to 9000 W m(-2) and mass flux from 13 to 66 kg m(-2) s(-1). The heat transfer coefficients were compared with 14 correlations found in the literature. The experimental heat transfer coefficients were higher than those predicted by many of the correlations. A correlation which was previously developed for a very large and long tube (21 mm diameter and 10 m long) was in good agreement with the experimental data (97% of the data within 30%). Several other correlations were able to predict the data within a reasonable deviation (within 30%) after some adjustments to the correlations.

  • 6.
    Fernando, W. Primal D.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Ameel, Tim
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    A minichannel aluminium tube heat exchanger - Part III: Condenser Performance with Propane2008In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 31, no 4, p. 696-708Article in journal (Refereed)
    Abstract [en]

    This paper reports heat transfer results obtained during condensation of refrigerant propane inside a minichannel aluminium heat exchanger vertically mounted in an experimental setup simulating a water-to-water heat pump. The condenser was constructed of multiport minichannel aluminium tubes assembled as a shell-and-tube heat exchanger. Propane vapour entered the condenser tubes via the top end and exited sub-cooled from the bottom. Coolant water flowed upward on the shell-side. The heat transfer areas of the tube-side and the shell-side of the condenser were 0.941 m(2) and 0.985 m(2), respectively. The heat transfer rate between the two fluids was controlled by varying the evaporation temperature while the condensation temperature was fixed. The applied heat transfer rate was within 3900-9500 W for all tests. Experiments were performed at constant condensing temperatures of 30 degrees C, 40 degrees C and 50 degrees C, respectively. The cooling water flow rate was maintained at 11.90 l min(-1) for all tests. De-superheating length, two-phase length, sub-cooling length, local heat transfer coefficients and average heat transfer coefficients of the condenser were calculated. The experimental heat transfer coefficients were compared with predictions from correlations found in the literature. The experimental heat transfer coefficients in the different regions were higher than those predicted by the available correlations.

  • 7.
    Fernando, W. Primal D.
    et al.
    KTH, Superseded Departments, Energy Technology.
    Palm, Björn
    KTH, Superseded Departments, Energy Technology.
    Granryd, Eric
    KTH, Superseded Departments, Energy Technology.
    Andersson, Klas
    KTH, Superseded Departments, Energy Technology.
    Mini-Channel Aluminium Heat Exchangers with Small Inside Volumes2003In: Proc. 21st IIR International Congress of Refrigeration, Washington DC, August 17-22, 2003, 2003Conference paper (Refereed)
  • 8.
    Fernando, W. Primal D.
    et al.
    KTH, Superseded Departments, Energy Technology.
    Palm, Björn
    KTH, Superseded Departments, Energy Technology.
    Granryd, Eric
    KTH, Superseded Departments, Energy Technology.
    Samoteeva, Oxana
    KTH, Superseded Departments, Energy Technology.
    Anderson, Klas
    KTH, Superseded Departments, Energy Technology.
    The Behaviour of Small Capacity (5kW) Heat pump with Micro-Channelled Flat Tube Heat Exchangers2002Conference paper (Refereed)
  • 9.
    Fernando, W. Primal D.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Performance of a single-family heat pump at different working conditions using small quantity of propane as refrigerant2007In: Experimental heat transfer, ISSN 0891-6152, E-ISSN 1521-0480, Vol. 20, no 1, p. 57-71Article in journal (Refereed)
    Abstract [en]

    The performance of a domestic heat pump that uses a low quantity of propane as refrigerant has been experimentally investigated. The heat pump consists of two minichannel aluminium heat exchangers, a scroll compressor, and an electronic expansion valve. It was charged with the minimum amount of refrigerant propane required for the stable operation of the heat pump without permitting refrigerant vapor into the expansion valve at incoming heat source fluid temperature to the evaporator of +10 degrees C The inlet temperature of the heat source fluid passing through the evaporator was varied from +10 degrees C to -10 degrees C while holding the condensing temperature constant at 35 degrees C, 40 degrees C, 50 degrees C, and 60 degrees C, respectively. The minimum refrigerant charges required at above-tested condensing temperatures were found to decrease when the condensing temperature increased and were recorded as 230 g, 224 g, 215 g, and 205 g, respectively. The results confirm that a heat pump with 5 kW capacity can be designed with less than 200 g charge of refrigerant propane in the system. Due to the high solubility of propane in compressor lubrication oil, the amount of refrigerant which may escape rapidly in case of accident or leakage is less than 150 g.

  • 10.
    Fernando, W. Primal D.
    et al.
    KTH, Superseded Departments, Energy Technology.
    Palm, Björn
    KTH, Superseded Departments, Energy Technology.
    Lundqvist, Per
    KTH, Superseded Departments, Energy Technology.
    Granryd, Eric
    KTH, Superseded Departments, Energy Technology.
    Propane Heat Pump with Low Refrigerant Charge: Design and Laboratory Tests2004In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 27, no 7, p. 761-773Article in journal (Refereed)
    Abstract [en]

    Independently of the choice of refrigerant, environmental and or safety issues can be minimised by reducing the amount of refrigerant charge per heat pump or refrigeration system. In the investigation reported here, a laboratory test rig was built, simulating a water-to-water heat pump with a heating capacity of 5 kW. The system was designed to minimize the charge of refrigerant mainly by use of mini-channel aluminium heat exchangers. It was shown that the system could be run with 200 g of propane at typical Swedish operating conditions without reduction of the COP compared to a traditional design. Additional charge reduction is possible by selecting proper compressor lubrication oils or by using a compressor with less lubrication oil.

  • 11.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Analytical expressions for optimum flow rates in evaporators and condensers of heat pumping systems2010In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 33, no 7, p. 1211-1220Article in journal (Refereed)
    Abstract [en]

    The flow velocities on the air or liquid side of evaporators and condensers in refrigerating or heat pump systems affect the system performance considerably. Furthermore the velocity can often be chosen rather freely without obvious first cost implications. The purpose of the paper is to show analytical relations indicating possible optimum operating conditions. Considering a base case where the design data are known, simple analytical relations are deduced for optimum flow rates that will result in highest overall COP of the system when energy demand for the compressor as well as pumps or fans are included. This optimum is equivalent to the solution for minimum total energy demand of the system for a given cooling load. It is also shown that a different (and higher) flow rate will result in maximum net cooling capacity for a refrigerating system with fixed compressor speed. The expressions can be used for design purposes as well as for checking suitable flow velocities in existing plants. The relations may also be incorporated in algorithms for optimal operation of systems with variable speed compressors.

  • 12.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Cooling and Refrigeration Load Calculations2011In: Sustainable Energy Utilisation / [ed] Havtun, H., Bohdanowicz, P., Stockholm: KTH Royal Institute of Technology, 2011, 300, p. 83-104Chapter in book (Other academic)
  • 13.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Heat Pumps: Technology and Applications2011In: Sustainable Energy Utilisation / [ed] Havtun, H., Bohdanowicz, P., Stockholm: KTH Royal Institute of Technology, 2011, 300, p. 219-260Chapter in book (Other academic)
  • 14.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Preservation of Food2011In: Sustainable Energy Utilisation / [ed] Havtun, H., Bohdanowicz, P., Stockholm: KTH Royal Institute of Technology, 2011, 300, p. 291-300Chapter in book (Other academic)
  • 15.
    Granryd, Eric G.
    KTH, Superseded Departments, Energy Technology.
    Hydrocarbons as refrigerants - an overview2001In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 24, no 1, p. 15-24Article in journal (Refereed)
    Abstract [en]

    Possibilities and problems of using hydrocarbons as working fluids in refrigerating equipment are discussed. An overview of safety standards is given. Different hydrocarbon alternatives are listed and characteristics in terms of thermodynamic cycles as well as heat transfer are shown. The general conclusion is that hydrocarbons offer interesting refrigerant alternatives for energy efficient and environmentally friendly refrigerating equipment and heat pumps. However, safety precautions due to flammability must be seriously taken into account. For some applications this can be done without adding noticeably to the total installation cost, but not in the general case.

  • 16. Granryd, Eric
    et al.
    Palm, Björn
    Värmeväxlarvägg anordnad med en tunn, hålförsedd metallfolie för att förbättra värmeövergången vid kokning respektive kondensation: [Heat transfer element]1986Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A heat exchanger wall incorporates a partition wall (11-12), one side of which is in contact with a heat exchange medium. A mechanically stable part (11) of the partition wall (11-12) has provided on one surface thereof a thin metal foil (12), which is provided with a large number of small through-passing holes (121) and which is attached directly to the said part (11), such as to form a minute gap (13) between the foil and the mechanically stable part. According to one embodiment the element comprises a tube (11) and the foil has provided therein a longitudinally extending slot (122) and/or a plurality of folds or bends (31, 32) directed towards the stable part (11), and/or a fold or bend (51) facing away from the stable part (11). In addition to occurring through the intrinsic rigidity of the foil, the thin gap is formed by providing one side of the foil (12) with a rough or irregular structure, or by forming the holes in the foil in a manner such as to leave burrs around the defining edges of the holes, or by providing in the foil a number of folds or bends (31, 32) which face towards the mechanically stable part.

  • 17.
    Melinder, Åke
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    IIR handbook on indirect refrigeration and heat pump systems2015In: Refrigeration Science and Technology, International Institute of Refrigeration, 2015, p. 2240-2247Conference paper (Refereed)
    Abstract [en]

    Indirect systems with secondary (working) fluid circuits are often used where there are many places to be cooled or where long pipes are required. Examples of systems with many places to be cooled are slaughter houses, dairies and breweries. Long pipes are common in air conditioning plants, artificial ice rinks and ground source heat pumps with long collector tubes in the ground. Indirect systems have often replaced systems with direct expansion within supermarket refrigeration, where the secondary fluid transports heat from cooling rooms or cabinets to achieve the right temperature of the products. Indirect systems are nowadays also used in freezer applications but more often with carbon-dioxide as phase changing secondary working media. Indirect systems have come in focus as requirements for tighter constructions are sharpened in order to minimize leakage of refrigerants from plants as well as the adjusted legislation to secure the phasing out of certain refrigerants. A Handbook on indirect systems was published in Swedish in 2010 in cooperation with over twenty companies and experts and an English translation has now been prepared to be published by the IIR. The chapters deal with the following topics: 1. Direct and indirect systems, 2. Indirect system solutions, 3. Components, 4. Secondary fluids, 5. Corrosion, 6. Environmental aspects, 7. Projecting and dimensioning, 8. Design and control of system, 9. System construction and installation and 10. Optimization of indirect systems. An expectation of all involved in producing the Handbook is that it will help to better understand and work with indirect systems. This paper is intended to give hints on what is covered in the Handbook!

  • 18.
    Melinder, Åke
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Granryd, Eric
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Using property values of aqueous solutions and ice to estimate ice concentrations and enthalpies of ice slurries2005In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 28, no 1, p. 13-19Article in journal (Refereed)
    Abstract [en]

    For ice slurry calculations and modeling, it is important that they are performed with accurate thermophysical property values of the aqueous solution and of ice. For ice slurry applications there is a need for accurate freezing point data and for more basic thermophysical property data at low concentrations. The article covers some phenomena in connection with freezing of aqueous solutions. Charts with ice concentration curves as a function of temperature and additive concentration are given for a number of aqueous solutions. A main purpose of using ice slurry is to benefit from the latent heat or enthalpy difference at melting. The article shows how an enthalpy-phase diagram can be constructed, gives charts with enthalpy values and charts giving apparent specific heat as a function of temperature and concentration for aqueous solution of propylene glycol, ethyl alcohol and potassium formate. These charts for ethyl alcohol-water are in good agreement with works earlier reported on.

  • 19. Navarro, E.
    et al.
    Granryd, Eric G.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Urchueguia, J. F.
    Corberan, J. M.
    A phenomenological model for analyzing reciprocating compressors2007In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 30, no 7, p. 1254-1265Article in journal (Refereed)
    Abstract [en]

    A new model for hermetic reciprocating compressors is presented. This model is able to predict compressor efficiency and volumetric efficiency in terms of a certain number of parameters (10) representing the main sources of losses inside the compressor. The model provides users with helpful information about the way in which the compressor is designed and working. A statistical fitting procedure based on the Monte Carlo method was developed for its adjustment. The model can predict compressor performance at most points with a maximum deviation of 3%. A possible gas condensation on cold spots inside the cylinder during the last part of the compression stroke was also evaluated.

  • 20. Navarro, E.
    et al.
    Urchueguia, J. F.
    Corberan, J. M.
    Granryd, Eric G.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Performance analysis of a series of hermetic reciprocating compressors working with R290 (propane) and R407C2007In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 30, no 7, p. 1244-1253Article in journal (Refereed)
    Abstract [en]

    In this paper, a series of compressors with different capacities and geometries working with propane as refrigerant are analyzed in terms of the compressor model developed by [E. Navarro, E. Granryd, J.F. Urchueguia, J.M. Corberan, A phenomenological model for analyzing reciprocating compressors, International Journal of Refrigeration, in this issue, doi:10.1016/j.irefrig.2007.02.006]. The relative influence of the diverse compressor losses is estimated as a function of the operating conditions. In addition, a comparison study between propane and R407C was carried out for one compressor and the observed differences were analyzed in terms of the compressor model. This study was also useful to verify the model's goodness with the aim of predicting the compressor performance with an untested refrigerant.

  • 21. Shao, D. W.
    et al.
    Granryd, Eric G.
    KTH, Superseded Departments, Energy Technology.
    Flow pattern, heat transfer and pressure drop in flow condensation part I: Pure and azeotropic refrigerants2000In: HVAC & R RESEARCH, ISSN 1078-9669, E-ISSN 1938-5587, Vol. 6, no 2, p. 175-195Article in journal (Refereed)
    Abstract [en]

    This study concerns the flow pattern, heat transfer, and pressure drop for flow condensation. The experimental results are recorded in tests with a smooth horizontal tube of 6 mm inner diameter and 2 to 10 m long. This manuscript, which is part I of a two part series, focuses on pure and azeotropic fluids. Part II describes results with non-azeotropic refrigerant mixtures. A flow pattern map by Tandon et al. (1982) roughly predicts flow patterns associated with pure and azeotropic fluids in this work. However, the Froude number is found to be a good additional indicator to identify transition between annular and wavy flows. The transition occurs mostly at Fr = 15 to 20 for both pure and azeotropic fluids. In the case of pure and azeotropic fluids, the hear transfer coefficient was found to be independent of the mass flux in wavy flow regions, but increased with an increasing mass flux in the annular flow regions. For pure and azeotropic fluids, a modified Tandon et al. correlation agreed best with experimental data from tests with R-12, R-22, R-134a, and R-502. For the local pressure drop it is correlated within +/-15% by using the Lockhart-Martinelli parameters. The experimental data for pure and azeotropic refrigerants can be predicted by using a correlation for overall pressure drop.

  • 22. Shao, D. W.
    et al.
    Granryd, Eric G.
    KTH, Superseded Departments, Energy Technology.
    Flow pattern, heat transfer and pressure drop in flow condensation part II: Zeotropic refrigerants mixtures (NARMs)2000In: HVAC & R RESEARCH, ISSN 1078-9669, E-ISSN 1938-5587, Vol. 6, no 2, p. 197-209Article in journal (Refereed)
    Abstract [en]

    This paper, which is parr II of a study on flow condensation is focused on zeotropic (or non-azeotropic) refrigerant mixtures (NARMs) In the experiments, condensation in a horizontal tube of inner diameter 6 mm and 10 m length were studied with fluids R-404A, R-407C, and three mixtures of R-32 and R-134a. A flow pattern map by Tandon et al. (1982) roughly predicts flow patterns associated with NARMs studied in this work. Most tests recorded are in the annular or semi annular flow region. The Froude number is, however, found to be an additional indicator to identify transition between annular and wavy flows. The transition in the experiments occurs mostly at Fr = 15 to 20 for the fluids tested. For NARMs with a small temperature glide (e.g. R-404A), as observed in the case of pure and azeotropic fluids, the hear transfer coefficient is independent of the mass flux in wavy flow regions, and increases with an increasing mass flux in annular flow regions. For other NARMs tested, the hear transfer coefficient (starting from a lower level) always increases with an increasing mass flux within the tested ranges. The heat transfer data from the tests with R-404A, R-407C, and R-32/R-134a mixtures can be predicted reasonably well by a modified Tandon et al. (1985b, 1995) equation with a correction proposed by Granryd (1989)for NARMs. The classical correlations for the pressure drop do nor work well. Instead, the data for local pressure drop are correlated within +/-15% by means of the same correlation as for the pure and azeotropic fluids. A simple correlation for the overall pressure drop based on the experimental data for pure and azeotropic fluids is good also for R-404A (with a small glide), but overpredicts the pressure drop (by up to 50%)for NARMs with glide, such as R-407C.

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