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  • 1.
    Grozdek, Marino
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Khodabandeh, Rahmatollah
    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.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Experimental investigation of ice slurry heat transfer in horizontal tube2009In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 32, no 6, p. 1310-1322Article in journal (Refereed)
    Abstract [en]

    Heat transfer of ice slurry flow based on ethanol-water mixture in a circular horizontal tube has been experimentally investigated. The secondary fluid was prepared by mixing ethanol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature -4.4 degrees C). The heat transfer tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 22% depending on test performed. Measured heat transfer coefficients of ice slurry are found to be higher than those for single phase fluid, especially for laminar flow conditions and high ice mass fractions where the heat transfer is increased with a factor 2 in comparison to the single phase flow. In addition, experimentally determined heat transfer coefficients of ice slurry flow were compared to the analytical results, based on the correlation by Sieder and Tate for laminar single phase regime, by Dittus-Boelter for turbulent single phase regime and empirical correlation by Christensen and Kauffeld derived for laminar/turbulent ice slurry flow in circular horizontal tubes. it was found that the classical correlation proposed by Sieder and Tate for laminar forced convection in smooth straight circular ducts cannot be used for heat transfer prediction of ice slurry flow since it strongly underestimates measured values, while, for the turbulent flow regime the simple Dittus-Boelter relation predicts the heat transfer coefficient of ice slurry flow with high accuracy but only up to an ice mass fraction of 10% and Re-cf > 2300 regardless of imposed heat flux. For higher ice mass fractions and regardless of the flow regime, the correlation proposed by Christensen and Kauffeld gives good agreement with experimental results. (C) 2009 Elsevier Ltd and IIR. All rights reserved.

  • 2. Hägg, Cecilia
    et al.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Lundqvist, Per
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Pressure Drop Experiments and Background for Choosing Suitable Fluid for Low Temperature Ice SlurrIn: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081Article in journal (Other academic)
  • 3.
    Hägg, Cecilia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Martin, C.
    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.
    A Proper Fluid for Ice Slurry at -35 ºC,2005Report (Other academic)
  • 4.
    Ignatowicz, M.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Melinder, Å.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, B,
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ethyl alcohol based secondary fluid: Effect of corrosion inhibitors on thermophysical properties2016In: Refrigeration Science and Technology, International Institute of Refrigeration , 2016, p. 602-609Conference paper (Refereed)
    Abstract [en]

    Currently available commercial ethyl alcohol (EA) based secondary fluids in Sweden and other Nordic countries contain up to 10 wt-% denaturing agents (in concentrate alcohol) in form of propyl alcohol and n-butyl alcohol but no corrosion inhibitors. These studies were initiated due to a growing need for providing any protection against corrosion and extending the lifetime of the system. A literature search has been made to find the compatible corrosion inhibitors that can effectively protect the system. Afterwards, measurements have been performed to investigate the effect of these corrosion inhibitors on the thermophysical properties of the base fluid. Results showed that the different corrosion inhibitors can affect the thermophysical properties even when added in small concentrations. The presences of corrosion inhibitor had a positive effect and decrease the freezing point. Additionally, the presence of corrosion inhibitor in 30 wt-% ethyl alcohol samples had no significant effect on the dynamic viscosity and only EA25 + 0.01 SG (sodium gluconate) sample showed lower dynamic viscosity value by up to 10 %. The corrosion inhibitors had negative effect on the thermal conductivity in the full temperature range. EA25 and EA30 samples containing sodium gluconate, benzotriazole and sodium molybdate had higher specific heat capacity than the pure solutions. This study showed that both benzotriazole and 2-mercaptobenzothiazole seem to be the most promising corrosion inhibitor for ethyl alcohol based secondary fluids.

  • 5.
    Ignatowicz, Monika
    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.
    Mazzotti, Willem
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Methods of BHE flushing, charging and purging in Sweden2016In: Proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    In Sweden, there are more than 500 000 small and about 500 relatively large ground source heat pumps (GSHP) having a total installed capacity of about 5.6 GW delivering approximately 15 TWh. yr-1 of heating and cooling energy in Sweden. The operational lifetime and reliability of any GSHP depends heavily on the way the system is designed, installed and operated. In order to provide a good system performance after installation, aspects such as borehole heat exchanger (BHE) system flushing, charging and purging, among others, should be taken into consideration. The aim of this work has been to review some existing methods of system flushing, charging and purging in order and make observations that may be applicable for the GSHP industry. Two Swedish case studies have been followed up and compared to existing strategies suggested by IGSHPA.The results show that there is a lack of specific recommendations regarding the flushing and purging procedures for BHEs in Sweden. A well-defined range or adaptation of similar IGSHPA standards could help in defining the minimum flush velocity. The two case studies showed different practices, with flushing velocities being significantly higher than the minimum flushing velocity recommended by IGSHPA. Flushing flow rates based on this standard are presented in this work for some typical BHE pipe sizes used in Europe.

  • 6.
    Ignatowicz, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mazzotti, W.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Acuña, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Melinder, A.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Alternative alcohol blends as secondary fluids for ground source heat pumps2016In: Refrigeration Science and Technology, International Institute of Refrigeration , 2016, p. 610-617Conference paper (Refereed)
    Abstract [en]

    The most common secondary fluid used for the borehole heat exchangers in Sweden is an aqueous solution of ethyl alcohol (EA) due to its relatively good thermophysical properties and low toxicity. Commercially available ethyl alcohol based fluids in Sweden contain up to 10 wt-% denaturing agents in form of propyl alcohol (PA) and n-butyl alcohol (BA). The aim of this paper was to investigate the performance of the existing ethyl alcohol blend containing two denaturing agents and alternative alcohol blends in terms of the pressure drop and heat transfer in the BHE and comparison with ethyl alcohol based secondary fluid. Experimental results showed that the presence of these denaturing agents improves thermophysical properties such as specific heat capacity, thermal conductivity and dynamic viscosity when added in small concentration. EA18 + PA1.6 + BA0.4 and EA18.4 + PA1.6 present the best characteristics in terms of the heat transfer and pressure drop. Both blends are giving higher heat transfer coefficient by 9.4 % (EA18 + PA1.6 + BA0.4) and 8.11 % (EA18.4 + PA1.6) than pure EA20. Both blends are giving as well lower pressure drop than EA20 by up to 2.7 % (EA18 + PA1.6 + BA0.4) and 3 % (EA18.4 + PA1.6). EA18 + PA1.6 + BA0.4 gives 1.4 % higher heat transfer coefficient and EA18.4 + PA1.6 gives lower pressure drop by up to 0.4 % when these two blends are compared.

  • 7.
    Ignatowicz, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mazzotti, Willem
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Acuña, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Melinder, A.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Different ethyl alcohol secondary fluids used for GSHP in Europe2017Conference paper (Refereed)
    Abstract [en]

    The most common secondary fluid used for the borehole heat exchangers in Sweden is aqueous solution of ethyl alcohol (EA). Commercially available ethyl alcohol based fluids in Sweden and other European countries contain various denaturing agents. Ethyl alcohol based secondary fluids in Sweden are distributed as ethyl alcohol concentrate, including up to 12 wt-% denaturing agents in form of propyl alcohol (PA) and n-butyl alcohol (BA). In other European countries, like Switzerland and Finland, the commercial products containing a mixture of methyl ethyl ketone and methyl isobutyl ketone (up to 4.5 vol-%) are used for GSHP application. The chemical character of these denaturing agents can in different ways affect the thermophysical properties. Therefore, the aim of this paper was to investigate the performance of commercially available alcohol blends in Europe in terms of pressure drop and heat transfer in the BHE. The results show that the most commonly used product in Sweden (EA18+PA1.6+BA0.4) presents the best characteristics in terms of higher heat transfer (up to 10 %) and lower pressure drop (up to 2.7 %) among different commercial products found in Europe. Another commercial product used in Switzerland showed second best performance in terms of higher heat transfer (up to 5 %) and lower pressure drop (up to 2 %). Moreover, other products containing higher concentrations of denaturing agents presented the worst performance in terms of lower heat transfer (up to 8 %) and higher pressure drop (up to 1 %) than EA20.

  • 8.
    Ignatowicz, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Mazzotti, Willem
    Rogstam, Jörgen
    Energi & Kylanalys.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Secondary Fluid Impact on Ice Rink Refrigeration System Performance2014Conference paper (Refereed)
    Abstract [en]

    Sweden has 352 ice rinks in operation which annually use approximately 1000MWh. A refrigeration system usually accounts for about 43% of the total energy consumption and can present a significant energy saving potential. More than 97% of the Swedish ice rinks use indirect refrigeration system and thermo-physical properties of secondary fluid have a direct impact on the heat transfer and pressure drop. A theoretical model and two case studies focusing on the importance of the secondary fluid choice were investigated. The results showed that potassium formate had the best heat transfer properties while ammonia lead to the lowest pressure drops and pumping power. Propylene glycol showed the worst performance in both cases. Ammonia and potassium formate showed respectively 5% and 3% higher COP than calcium chloride for typical heat loads of 150kW. When controlling the pump over a temperature difference (ΔT), the existence of the optimum pump control or optimum flow was highlighted. For typical cooling capacity of 150kW optimum pump control temperature difference ΔT was around 2,5K for calcium chloride and around 2K for ammonia. Järfälla case study showed a potential energy saving of 12% for the refrigeration system when increasing the freezing point of the secondary fluid. An energy saving of around 10,8 MWh/yr per 1K increase of the secondary fluid freezing point was found.

  • 9.
    Ignatowicz, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Melinder, Åke
    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.
    Ethyl and isopropyl alcohol blends as alternative secondary fluids2015In: Refrigeration Science and Technology, International Institute of Refrigeration, 2015, p. 2224-2231Conference paper (Refereed)
    Abstract [en]

    Methyl and ethyl alcohol based secondary fluids are commonly used in different indirect refrigeration systems due to relatively good thermophysical properties. Methyl alcohol is considered toxic and not permitted for use as secondary fluid in most of Europe. Ethyl alcohol based secondary fluids are commonly used in Sweden due to their low toxicity and good properties. Commercially available ethyl alcohol based fluids contain up to 10 wt-% denaturing agents in form of propyl alcohol (2-propanol, isopropanol) and nbutyl alcohol (n-butanol). Results show that presence of propyl alcohol in the ethyl alcohol based secondary fluid improves its thermophysical properties such as specific heat capacity, thermal conductivity and dynamic viscosity when added in small concentration. The aim of this paper is to investigate the thermophysical properties of various ethyl and isopropyl alcohol blends in order to find the most optimal blend as well as to evaluate if this blend could become a competitive alternative secondary fluid.

  • 10.
    Ignatowicz, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Melinder, Åke
    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.
    Evaluation of thermophysical properties of ethyl alcohol based secondary fluids2014In: 11th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerants and Environmental Protection, GL 2014, 2014, p. 100-107Conference paper (Refereed)
    Abstract [en]

    Ethyl alcohol (ethanol) based secondary fluids are commonly used in different types of indirect refrigeration systems in Scandinavia due to low toxicity, relatively good thermophysical properties and environmental regulations regarding leakage. Ethyl alcohol based commercial products available in Scandinavia contain different types of denaturing agents but no corrosion inhibitors. The most common denaturing agents are isopropyl alcohol (isopropanol), n-butyl alcohol (n-butanol), methyl ethyl ketone and methyl isobutyl ketone. Property measurements recently performed at KTH showed that presence of these additives in ethyl alcohol based secondary fluid improved thermophysical properties especially in terms of specific heat, thermal conductivity, and dynamic viscosity. Additionally, it was found that the specific heat capacity tendency is different than previously reported.

  • 11.
    Ignatowicz, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Melinder, Åke
    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.
    MEASUREMENTS OF STANDARD SEAWATER CALLS FOR MINOR ADJUSTMENTS OF SEAWATER ICE SLURRY PROPERTIES2016In: 11TH IIR CONFERENCE ON PHASE CHANGE MATERIALS AND SLURRIES FOR REFRIGERATION AND AIR CONDITIONING / [ed] Kauffeld, M, 2016, p. 162-170Conference paper (Refereed)
    Abstract [en]

    Seawater is the most common fluid on earth and ice generating machines are increasingly used on fishing vessels to produce ice slurry from the seawater with up to 60 % ice to be poured over the catch. In this study, new measurements of thermophysical properties of standard seawater have been carried out to complement a recent literature search made to establish thermophysical property data of seawater as function of salinity and temperature. These single-phase measurements have been made for salinity 20, 30 and 35 g kg(-1) (2.0, 3.0 and 3.5 % total salt content) and include measurements of freezing point, density, dynamic viscosity, thermal conductivity, specific heat capacity and specific enthalpy. The obtained experimental results generally confirm recent literature search and experimental results only call for minor adjustments of viscosity values. Hence, experimental results confirm the following published ice slurry properties: enthalpy, ice fraction and ice slurry density.

  • 12.
    Melinder, Åke
    KTH, Superseded Departments, Energy Technology.
    A Critical Review on Thermophysical Properties of Liquid Secondary Refrigerants1998In: Natural Working Fluids '98: proceedings, 1998Conference paper (Other academic)
  • 13.
    Melinder, Åke
    KTH, Superseded Departments, Energy Technology.
    Comparing properties of aqueous solutions for liquid only and ice slurry applications of indirect systems2003In: 21st International congress of refrigeration: proceedings, 2003Conference paper (Other academic)
  • 14.
    Melinder, Åke
    KTH, Superseded Departments, Energy Technology.
    Enthalpy-phase diagrams of aqueous solutions for ice-slurry applications2002In: Proc. of the Fifth workshop on Ice slurries of the International Institute of Refrigeration, 2002Conference paper (Other academic)
  • 15.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Equilibrium properties of ice slurry based on two chosen types of aqueous solutions2006In: 7th IIR Conference on Phase Change materials and Slurries for Refrigeration and Air Conditioning , Dinan, France, 2006Conference paper (Other academic)
  • 16.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Estimating optimal ice slurry properties using simple equations and properties of the aqueous solution2011In: 23rd International-Institute-of-Refrigeration, 2011, p. 919-926Conference paper (Refereed)
    Abstract [en]

    Aqueous solutions used as single-phase secondary fluids can also be used below the freezing point as ice slurry, a fluid consisting of liquid and ice. It is not as easy to determine thermophysical properties when aqueous solutions are used as two-phase ice slurry as when used for single-phase liquids. One main reason is that ice particles in a system change form and size with time. Values obtained from measurements in lab rigs are strictly valid only for the batch in case and at that specific time. Results from experiments done over the years in various lab rigs in research centres have often been compared to what equations for liquids with solid particles give although the values at times differ much. Such equations may be used to compare ice slurry properties for different fluid types and to find optimal conditions in a particular application. This paper presents ice fraction, density, enthalpy, viscosity and thermal conductivity for aqueous solutions of ethylene glycol and potassium formate based on fluid properties and mentioned equations. Diagrams help us compare the fluids for certain operational temperatures and initial freezing point temperatures or additive fractions. The relative differences between fluids and operational conditions will likely be similar to what ice slurry in a real plant gives, providing valuable clues for choice of fluid and suitable operational conditions. A conclusion from examples given is that the best performance is obtained with an initial freezing point equal to the operation temperature at the end of the user unit, giving maximal change in ice fraction and enthalpy. The dynamic viscosity does not differ very much from the viscosity of single-phase while the thermal conductivity is higher. The high density of potassium formate may give less even distribution of ice in pipes.

  • 17.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Properties and other aspects of aqueous solutions used for single phase and ice slurry applications2010In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 33, no 8, p. 1506-1512Article in journal (Refereed)
    Abstract [en]

    Indirect systems with aqueous solution have long been used to minimize the charge and leakage of (primary) refrigerants. In ice slurry applications such aqueous solutions are used below the freezing point, benefitting from the enthalpy change resulting from ice melting. Accurate thermophysical property data and a general knowledge of other secondary fluid properties are useful for selection of fluid and for technical calculations of the system. This paper introduces a new IIR publication, Properties of secondary working fluids for indirect systems. Tables and charts with fluid properties, property relations of ice and of ice slurry, enthalpy-phase diagrams and related charts are here given for sodium chloride and water, as an example. This new IIR publication that also considers corrosion aspects and environmental impact of such fluids is intended to be used by industry and researchers working with single phase as well as ice slurry applications.

  • 18.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    PROPERTIES AND OTHER ASPECTS OF AQUEOUS SOLUTIONS USED FOR SINGLE-PHASE AND ICE SLURRY APPLICATIONS2009In: 8TH IIR CONFERENCE ON PHASE CHANGE MATERIALS AND SLURRIES FOR REFRIGERATION AND AIR CONDITIONING / [ed] Kauffeld, M., PARIS: INT INST REFRIGERATION , 2009, p. 51-58Conference paper (Refereed)
    Abstract [en]

    Indirect systems with aqueous solution used as secondary working fluids (secondary refrigerants or coolants) have long been used making it possible to minimize the charge and leakage of (primary) refrigerant. In ice slurry applications such aqueous solutions are used below the freezing point, benefiting from the enthalpy change resulting from ice melting. Accurate thermophysical property data and a general knowledge of other secondary fluid properties are useful for choice of suitable fluid and for technical calculations of the system. An extensive research with the aim to establish reliable data resulted in an IIR publication (Melinder 1997). Since then work has been carried out to update and extend such data for a new IIR publication intended to be published in 2009. Property values have been included for lower concentrations of the additive where ice slurries have best potential. Two tables arc as an example here given for aqueous solutions of sodium chloride. One table gives density, mixing properties, index of refraction, surface tension and specific conductance at 20 C. The other table gives thermophysical fluid properties, here only for low concentrations. Polynomial equations and coefficients used in an Excel-program for simple technical calculations are outlined. The new IIR publication includes other properties and aspects of the aqueous solutions used and it considers corrosion and material compatibility as well as environmental impact of such fluids. A summary is given with characteristics of aqueous solutions used for ice slurries. Property relations are given of ice and of fine crystalline ice slurry as well as enthalpy phase diagrams and charts with equilibrium values of ice mass fraction, enthalpy and density of ice slurries of sodium chloride and water. Hopefully this new IIR publication will prove to be useful for industry and researchers working with single-phase as well as ice slurry applications.

  • 19.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Properties of various secondary fluids for supermarket applications2005In: IIR International Conference Thermophysical Properties and Transfer Processes of Refrigerants, Refrigeration Science and Technology Proceedings: Commercial Refrigeration/Thermophysical Properties and Transfer Processes of Refrigerants, 2005 August 31–September 2; Vicenza, Italy, 2005Conference paper (Other academic)
  • 20.
    Melinder, Åke
    KTH, Superseded Departments, Energy Technology.
    Secondary fluids for low operating temperatures2004In: 6th IIR-Gustav Lorentzen Natural Working fluids, Glasgow, August 29–September 1, 2004, 2004Conference paper (Other academic)
  • 21.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids2007Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Secondary working fluids (secondary refrigerants, heat transfer fluids, antifreezes, brines) have long been used in various indirect re-frigeration and heat pump systems. Aqueous solutions (water solu-tions) have long been used as single phase (liquid only) secondary working fluids for cooling in supermarkets, ice rinks, heat recovery systems, heat pumps and other applications. However, aqueous solutions are increasingly used also for freezers in supermarkets and other applications in low temperature refrigeration.

    Of importance when comparing different secondary working fluids for indirect systems are the following basic thermophysical properties: freezing point, density, viscosity, specific heat, and thermal conductivity. Reliable data of these properties are needed to choose suitable fluid and to make technical calculations of an indirect refrigeration or heat pump system.

    The main intention of this work has been to select thermophysical property data with good or acceptable technical accuracy of a number of aqueous solutions that can be used by the refrigeration and heat pump industry, rather than focusing on a limited number of property values or scientifically very accurate measuring techniques.

    A thorough literature search was in view of this made to find the most reliable property values of aqueous solutions. Detailed literature references are given for thermo-physical properties of the following aqueous solutions, without other additives: Ethylene and propylene glycol, ethyl and methyl alcohol, glycerol, ammonia, potassium carbonate, calcium, lithium, magnesium and sodium chlorides as well as potassium acetate and potassium formate. Some laboratory measurements were made of most of the fluid types when literature values were incomplete or deemed unreliable. Methods used are briefly described and results are given.

    Much of the work was reported on in the Engineering Licentiate Thesis: Thermophysical properties of liquid secondary refrigerants, A Critical Review on Literature References and Laboratory Measure-ments (Melinder 1998a). That material forms the basis for the charts and tables used in the IIR-publication Thermophysical properties of liquid secondary refrigerants (Melinder, 1997). The present thesis reports on an update made since 1998, including re-view work done on two additional fluids not covered in Melinder (1998a).

    The thesis describes how the selection of property values results in tables and charts intended for the industry. Coefficients for poly-nomial equations are generated from these property values using a Matlab program and this material is intended as a useful tool for computer treatment. Aqueous solution of ethyl alcohol is used as example to see how this process is made. This choice of fluid can also be seen as a test of this method, as the basic thermophysical properties of aqueous solutions of ethyl alcohol present more chal-lenges than the other fluids examined.

    A comparison is made of a few types of aqueous solutions used as secondary working fluids for two types of applications. The first example is bedrock heat pumps and the second is cooling cabinets in a supermarket. An effort is made to see how the additive con-centration affects the thermal performance.

    Most aqueous solutions used as single-phase secondary fluids can also be used as ice slurry, a fluid consisting of liquid and ice where small ice crystals are produced, usually with some type of ice generator. The ice crystals are then transported to the cooling object from which heat is removed when ice crystals melt. This results in less temperature change in the cooling object and makes it also possible to reduce the volume flow rate and to use smaller pipe dimensions in the system.

    In order to choose a secondary fluid for ice slurry use and to make correct technical calculations of the ice slurry system there is a need to examine and evaluate thermo-physical properties and other aspects of ice and of the aqueous solution used. For dimensioning purposes it is of interest to estimate ice mass fraction and enthalpy values and enthalpy-phase diagrams can serve that purpose. This thesis presents enthalpy-phase diagrams made by author that besides isotherms contain lines with ice fraction and lines connecting enthalpies at freezing point and 1, 2, etc. to 10 K below the freezing point curve.

  • 22.
    Melinder, Åke
    KTH, Superseded Departments, Energy Technology.
    Thermophysical properties of liquid secondary refrigerants: a critical review on literature references and laboratory measurements1998Licentiate thesis, monograph (Other scientific)
  • 23.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Tools for a successful use of secondary working fluids in indirect systems2011In: 23rd International-Institute-of-Refrigeration, 2011, p. 903-910Conference paper (Refereed)
    Abstract [en]

    Most refrigeration systems have been constructed as direct expansion systems but indirect systems with secondary circuits have long been used. Today, indirect systems with secondary (working) fluids (secondary refrigerants or coolants, heat transfer fluids, brines) are used for a number of applications from solar heating to freezers in supermarkets. What needs to be considered when using secondary fluids in indirect systems? This paper takes up two rather new publications and a DVD that have been produced as tools for a successful use of secondary working fluids in indirect systems. One publication, Properties of Secondary Working Fluids for Indirect Systems (Melinder 2010), covers thirteen types of aqueous solutions and includes a few non-aqueous heat transfer fluids as a comparison. The fluid should be chosen considering the thermal properties at the operation temperature and certain other aspects such as toxicity, environmental impact and the effect of corrosion on metals and other materials in the system. A comparison of the fluid types is given for several applications. Properties of phase changing secondary working media or fluids are considered, evaporating CO2 to some extent and ice slurry properties more extensively. The publication contains an extensive section with tables and charts of thermo-physical properties of the various types of aqueous solution. A DVD includes an Excel calculation program using equations presented in the publication and an Excel prop-am to make fluid property values available for computer programs of the user. The second publication on indirect refrigeration and heat pump system has been produced in Swedish in cooperation with over twenty companies and persons involved in the field (Melinder 2009). Information from books, reports, magazine articles, company information has been taken in consideration. An English version, Handbook on indirect refrigeration and heat pump systems, is planned to be published in the near future. The chapters in this handbook deal among else with the following topics: direct contra indirect systems, indirect systems solutions, components in secondary circuits, secondary (working) fluids, corrosion, environmental aspects, design, dimensioning, construction, installation, control and optimization of indirect systems. An expectation is that this handbook will prove to be a useful tool to understand and work with indirect systems.

  • 24.
    Melinder, Åke
    KTH, Superseded Departments, Energy Technology.
    Update on Indirect Systems and Secondary Fluids with Focus on Supermarket Refrigeration2003In: FTEC 2003, 2003Conference paper (Other academic)
  • 25.
    Melinder, Åke
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Updating and extending secondary fluid data for various refrigeration and heat pump applications2006In: GLC 2006 Trondheim, 2006Conference paper (Other academic)
  • 26.
    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!

  • 27.
    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.

  • 28.
    Melinder, Åke
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ignatowicz, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Properties of seawater with ice slurry use in focus2014In: 11th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerants and Environmental Protection, GL 2014, 2014, p. 865-873Conference paper (Refereed)
    Abstract [en]

    Seawater is the most common fluid on earth and ice generating machines are increasingly used on fishing vessels to produce ice slurry from seawater with up to 60% ice to be poured over the catch. An experiment using this method has recently shown that sensitive fish immersed in ice slurry, when flown from Japan to Taiwan, arrived in better condition than fish chilled by ordinary procedure. In this study, a literature search has been made to establish physical property data of seawater as function of salinity and temperature. Ice slurry properties of seawater have been generated and are presented by means of an enthalpy-phase diagram and related tables with ice concentration, enthalpy change and density. This material confirms that an initial salt content of 2-3 % is optimal and it can help determine the potential for long preservation of catch on board and during transport. As seawater is known to be corrosive, a brief discussion on corrosion factors and problems, the use of corrosion inhibitors and choice of machine and transport materials is included in this paper.

  • 29.
    Melinder, Åke
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Ignatowicz, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Properties of seawater with ice slurry use in focus2015In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 52, p. 51-58Article in journal (Refereed)
    Abstract [en]

    Seawater is the most common fluid on earth and ice generating machines are increasingly used on fishing vessels to produce ice slurry from seawater with up to 60% ice to be poured over the catch. In this study, a literature search has been made to establish physical property data of seawater as function of salinity and temperature. Ice slurry properties of seawater have been generated and are presented by means of an enthalpy-phase diagram and related tables with ice concentration, enthalpy change and density. This material confirms that an initial salt content of 2-3 % is optimal and it can help determine the potential for long preservation of catch on board and during transport, improving seafood quality. As seawater is known to be corrosive, a brief discussion on corrosion factors and problems, the use of corrosion inhibitors and choice of materials is included in this paper.

1 - 29 of 29
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