1、 International Journal of Heating, Ventilating, Air-conditioning and Refrigerating Research Editor John W. Mitchell, Ph.D., P.E. Professor of Mechanical Engineering, University of Wisconsin-Madison, USA Associate Editors Michael J. Brandemuehl, Ph.D., P.E., Professor, Joint Center for Energy Managem
2、ent, University of Colorado, Boulder, USA James E. Braun, Ph.D., P.E., Associate Professor, Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA Alberto Cavallini, Ph.D., Professor, Dipartmento di Fisicia Tecnica, University of Padova, Italy
3、Arthur L. Dexter, D.Phil., C.Eng., Reader in Engineering Science, Department of Engineering Science, University of Oxford, United Kingdom Leon R. Glicksman, Ph.D., Professor, Departments of Architecture and Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, USA Richard R. Gonz
4、alez, Ph.D., Director, Biophysics and Biomedical Modeling Division, US. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA Anthony M. Jacobi, Ph.D., Associate Professor and Associate Director ACRC, Department of Mechanical and Industrial Engineering, University of Illinois
5、, Urbana-Champaign, USA Reinhard Radermacher, Ph.D., Professor and Director, Center for Environmental Energy Engineering, Department of Mechanical Engineering, University of Maryland, College Park, USA Keith E. Starner, P.E., Engineering Consultant, York, Pennsylvania, USA Jean-Christophe Visier, Ph
6、.D., Head, Centre Scientifique et Technique du Btiment, Energy Management Automatic Controller Division, Mame La Valle, France Policy Committee Lee W. Burgett, Chair Jack B. Chaddock Ken-Ichi Kimura John W. Mitchell Frank M. Coda W. Stephen Comstock Editorial Assistant Publisher ASHRAE Staff Jennife
7、r A. Haukohl W. Stephen Comstock Mark S. Owen, Handbook Editor Barry Kurian, Publishing Services Manager Heather Kennedy, Handbook Associate Editor Nancy F. Thysell, Typographer 02001 by the American Society of Heating, Refrigerating and Air- Conditioning Engineers, Inc., 1791 Tullie Circle, Atlanta
8、, Georgia 30329. All rights reserved. Periodicals postage paid at Atlanta, Georgia, and additional mailing offices. HVAC nor may any part of this book be reproduced, stored in a retrieval system, or transmitted in any form or by my means-electronic, photocopying, recording, or other-without permissi
9、on in writing from ASHRAE. Abstracts-Abstracted and indexed by ASHRAE Abstract Center; Ei (Engineering Information, Inc.) Ei Compendex and Engineering Index; IS1 (Institute for Scientific Information) Web Science and Research Alert; and BSRlA (Building Services Research publication of the bibliograp
10、hical bimonthly IZR Bulletin that contains, among other things, a review article and a news section; regular update of the electronic database Fridoc; publication of a highly scientific journal, the International Journal of Refrigeration; release of recommen- dations for governments; publication of
11、IIR conference proceedings and technical manuals; set- ting up international working parties to provide informed advice on specific issues such as Ice Slurries and Code of Practice on Quick-Frozen Foods; maintenance of an information resources department; organization of periodic training sessions t
12、o meet the needs of countries requesting courses; and awarding prizes. The IIR International Congress of Refrigeration returns to Washington, D.C., after the suc- cessful Congress of 1971, held in the same site for the second time in the U.S. (Chicago had hosted the 3rd edition of the congress in 19
13、13). The organization of ICR2003 is under way as part of the U.S. National Committee (USNC) for the IIR. This represents the most significant activity of this board after its revitalization several years ago. Long before the IIR International Congress of Refrigeration was held in Sydney, Australia,
14、in September 1999, a core organizing committee was established within the USNC under the chair- manships of Dr. Jerry Groff and M. Mark Menzer, with Drs. Ray Cohen and Eckhard Groll as Co-chairmen of the Program Committee. Since the very beginning, ASHRAE, NIST, the U.S. Departments of Agriculture a
15、nd of Energy, ARI, and IIAR together with other key organizations and companies endorsed and served as sponsors for the congress, a joint effort that produced a most successful event. Since any refrigeration congress can be considered as the concluding summit of the four-year periods marking the lif
16、e of the IIR, each commission president has been requested to select a particular theme that can be used to focus commission activities and conferences during the period leading up to the congress. The same themes will be used as a basis for organization of the conference program. The themes selecte
17、d within Sections B and E, those treating topics closer to the scientific interest of this journals readers, reflect as expected the main issues facing refrigeration. They are entitled Environment-Friendly Refrigerants, Their Thermophysical Properties and Heat Transfer Characteristics for Commission
18、 B 1; New Fluids, New Systems, and System Integration for Commission B2; Engineering Better Working and Living Environ- ments for Commission El; and Energy-Ejjcient Heating and Cooling Systems for Buildings for Commission E2. All the activities organized under the umbrella of the International Insti
19、tute of Refrigeration, reflecting its intergovernmental structure and history, affect and involve most of the countries of the world. Globalization is not a recent discovery, but a long-lived word in the IIR dictionary. In this context, the ICR2003 Congress will represent a unique forum attended by
20、over a thousand of the worlds leading refrigeration researchers, engineers, government officials, and users; a full week of technical sessions, seminars, workshops, courses, and, of course, social events. Attendees are the people who will influence the future direction of research, markets, and prod
21、- ucts in developed countries as well as in the fast developing regions of Asia, Africa, the Middle East, and Latin America. There are many good reasons to join ICR2003 in Washington, D.C., in August 2003 (http:/www.icr2003.org). VOL. 7, No. 4 HVAC Schwartzberg 1976; Chen 1985a, 1987, 1988; Pham 198
22、7; Pham et al. 1994; Murakami and Okos 1996), assuming that Raoults law is valid. The freezing point depression equation is then given by - MWL, RT d dT(lnxw) = which can be integrated to yield where x, is the mole fraction of water in solution, M, is the molar mass of water, Lo is the latent heat o
23、f fusion of water, R is the ideal gas constant, To is the freezing point of water, and Tis the freezing point of the food. In addition, the mole fraction of water in solution, x, is given by WWMW x, = w,/M, + w,/Ms (4) An effective molar mass M, for the solids is used since it would be difficult to
24、determine the actual molar mass of the soluble solids. This effective molar mass is empirically determined from freezing point data so as to correlate with experimentally determined ice content data. 314 HVAC Lo = 333 600 Jkg m parameter in Equation (19) M parameter in Equation (47): M = L2( 1 - kd
25、/kc) M, effective molar mass of food solids (kg/mol) M, molar mass of water (kg/mol) n parameter in Equations (6) and (7) n parameter in Equation (19) N2 volume fraction of discontinuous phase P parameter in Equation (49): P = N( 1 - kd/kc ) VOLUME 7, NUMBER 4, OCTOBER 2001 329 R t food temperature,
26、 “C 9 t, reference temperature, “C T food temperature, K Tf To T, reference temperature, K T reduced temperature V, Vd volume of discontinuous phase, m3 w1 mass fraction of component 1 wb mass fraction of bound water wi mass fraction of ith food component wice mass fraction of ice wp mass fraction o
27、f protein w, mass fraction of solids wso mass fraction of soluble substances ideal gas constant: R = 8.314 J/(mol.K) initial freezing temperature of food, “C initial freezing point of food item, K freezing point of water: To = 273.2 K - volume of continuous phase, m3 wu mass fraction of insoluble su
28、bstances w, mass fraction of unfrozen water w, mass fraction of water in unfrozen food x, mole fraction of water in solution y correlation parameter in Equation (36) z correlation parameter in Equation (36) a Rahman-Chen structurai factor Ac difference in specific heat capacities of water and ice; A
29、c = c, - cice, J/(kg. K) volume fraction of component 1 a volume fraction of air within food item volume fraction i“ food component $, volume fraction of water within food item A thermal conductivity ratio; A = kl/k2 pi density of component 1, kg/m3 p2 density of component 2, kg/m3 pi density of ith
30、 food component, kg/m3 (T parameter given by Equation (52) REFERENCES ASHRAE. 198 i. ASHRAE Handbook-Fundamentals. Atlanta, Georgia: American Society of Heating, Chang, H.D. and L.C. Tao. 1981. Correlations of Enthalpies of Food Systems. Journal of Food Science Charm, W.E. 197 1. Fundamentals of Foo
31、d Engineering, 2nd edition, Westport, Connecticut: Avi Publish- ing Co. Chen, C.S. 1985a. Thermodynamic Analysis of the Freezing and Thawing of Foods: Enthalpy and Appar- ent Specific Heat. Journal of Food Science 50(4):1158-1162. Chen, C.S. 1985b. Thermodynamic Analysis of the Freezing and Thawing
32、of Foods: Ice Content and Mol- lier Diagram. Journal of Food Science 50(4): 1163-1 166. Chen, C.S. 1987. Relationship Between Water Activity and Freezing Point Depression of Food Systems. Journal of Food Science 52(2):433-435. Chen, C.S. 1988. Systematic Calculation of Thermodynamic Properties of an
33、 Ice-Water System at Subfreezing Temperatures. Transactions of the ASAE 31 (5): 1602-1606. Choi, Y., and M.R. Okos. 1986. Effects of Temperature and Composition on the Thermal Properties of Foods. In Food Engineering and Process Applications 1 :93-101. London: Elsevier Applied Science Publishers. De
34、lgado, A.E., A.C. Rubiolo, and L.M. Gribaudo. 1990. Effective Heat Capacity for Strawberry Freezing and Thawing Calculations. Journal of Food Engineering 12(3): 165-175. Eucken, A. 1940. Allgemeine Gesetzmassigkeiten fr das Warmeleitvermogen verschiedener Stoffarten und Aggregatzustande. Forschung a
35、uf dem Gebiete des Ingenieurwesens, Ausgabe A 1 i( 1):6. Fikiin, K.A. 1996. Ice Content Prediction Methods During Food Freezing: A Survey of the Eastern Euro- pean Literature. In New Developments in Refrigeration for Food Safety and Quality, International Institute of Refrigeration, Paris, France, a
36、nd American Society of Agricultural Engineers, St. Joseph, Michigan, pp. 90-97. Fleming, A.K. 1969. Calorimetric Properties of Lamb and Other Meats. Journal of Food Technology 4: 199. Heldman, D.R. 1974. Predicting the Relationship Between Unfrozen Water Fraction and Temperature Dur- ing Food Freezi
37、ng Using Freezing Point Depression. Transactions of the ASAE 17( 1):63-66. Holland, B., A.A. Welch, I.D. Unwin, D.H. Buss, A.A. Paul, and D.A.T. Southgate. 1991. McCance and Widdowsons-The Composition of Foods. Cambridge, U.K.: Royal Society of Chemistry and Minis- try of Agriculture, Fisheries and
38、Food. Refrigerating and Air-conditioning Engineers. 46(5): 1493-1497. 330 HVAC Wijaya 1991), but the oil concentrations in the flowing fluid were unknown. Additionally, these studies speculated on the nature of oil effects, but experimental data were lacking to verify their conclusions. These facts,
39、 together with the importance of the expansion device for the system (Thome 1997; Thome et al. 1996), constitute the motivation for the modeling effort done by Yana Motta (1995) and for the present experimental study. An extensive literature review has been carried out to define the objectives and g
40、oals for the present study. This review is presented in chronological order, covering articles related to the flow of refrigerantlo2 mixtures through capillary tubes and short tube orifices. The short tube has been included because of its similarity to capillary tubes (expansion devices of fixed Sam
41、uel F. Yana Motta is a senior staff engineer for Honeywell inc., Buffalo Research Laboratory, Buffalo, New York. Sergio Leal Braga and Jos Alberto dos Reis Panse are associate professors in the Department of Mechanical Engi- neering, Catholic University of Rio de Janeiro, Brazil. 33 1 332 HVAC and (
42、2) The measurements of temperature and pres- sure profiles showed a delay in the vaporization point. However, this phenomenon is typical of the refrigerant contamination with oil (decrease of the bubble pressure or a delay in the begin- ning of vaporization). Consequently, there is no certain conclu
43、sion whether this delay is caused by the oil presence in the flowing fluid or by the existence of the metastable phenomenon. MacLaren (1971) published an experimental study on the flow of R-l2/oil solutions through adiabatic capillary tubes. This work was the first to state that the oil-contaminated
44、 refrigerant properties differ greatly from those of the pure refrigerant. Apparently, this author took the R-12/oil solution from the oil separator (installed at the compressor discharge), using it to fill a reservoir connected to the compressor crankcase by a capillary tube. Using this configurati
45、on, he was able to evaluate the flow of R-12/oil solutions through the capillary tube, though no means of controlling the oil concentration was available at that time. Despite this difficulty, some results were obtained showing a decrease of the mass flow rate with an increase in oil concentration.
46、Wijaya (1991) performed an experimental evaluation removing the oil separator from the sys- tem, but the oil concentration in the flowing fluid was unknown. These results were presented in graphical form (mass flow vs. condensation temperature), and showed no significant difference between pure and
47、contaminated flow. However, the calculation of the condensation temperature was made based on the measured pressure using the properties of the pure fluid rather than the properties of the refrigeranvoil mixture. Kim and ONeal (1994) studied the flow of refrigerantloil mixtures through short tube or
48、i- fices. In this study, the oil concentration was up to 5.1%, and the fluids studied were R-22 and R- 134a. Experimental data were collected for a mixture of R-134a with synthetic oil (polyalky- lene glycol). Measurements of temperature, pressure, and mass flow rate were taken for oil con- centrati
49、ons of O%, 2.1%, and 5.1%. Additionally, a glass short tube allowed a visual analysis of the flow. The authors concluded that the critical flow rate is affected by the presence of oil, but vaporization delay does not play an important role compared to the effects of the higher viscos- ity and surface tension of the refrigeradoi1 mixture. The results obtained in this research did not show a definite trend, except for the 5.1% oil concentration: the mass flow increases slightly VOLUME 7, NUMBER 4, OCTOBER 2001 333 (less than 3%) for d
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