EXPERIMENTAL INVESTIGATION ON BOILING HEAT TRANSFER USING R134A

Journal for Research| Volume 02| Issue 03 | May 2016 ISSN: 2395-7549

Experimental Investigation on Boiling Heat Transfer using R134A Ankit Tandel PG Student MGITER

Hiren Patel Assistant Professor MGITER

Dhaval Tandel Assistant Professor MGITER

Jenip Tandel Assistant Professor GEC Valsad

Abstract The heat transfer characteristic of R134a during boiling were experimentally investigated in a horizontal mini channels. The experiments used different parameters like saturation temperature, mass flux, vapour quality, channel diameter, channel geometry and thermo physical properties on the heat transfer coefficients. Several literatures are used to find a assessment correlations and experimental analysis to prepare an experimental setup and their results validation. Boiling heat transfer correlations and theoretical solutions are used to predict the experimental data in this research.

Keywords: Heat transfer coefficient; Mini channel; Boiling; Reynold number; Hydraulic diameter; vapour quality _______________________________________________________________________________________________________ I.

INTRODUCTION

Boiling Heat Transfer: When the temperature of a liquid at a specified pressure is raised to the saturation temperature at that pressure, boiling occurs.

Boiling is classified as pool boiling or flow boiling, depending on the presence of bulk fluid motion. Boiling is called pool boiling in the absence of bulk fluid flow and flow boiling in the presence of it.

Pool and flow boiling are further classified as sub cooled boiling or saturated boiling, depending on the bulk liquid temperature. Boiling is said to be sub cooled (or local) when the temperature of the main body of the liquid is below the saturation temperature T sat (i.e., the bulk of the liquid is sub cooled) and saturated (or bulk) when the temperature of the liquid is equal to T sat (i.e., the bulk of the liquid is saturated).

II. LITERATURE REVIEW [P11]

S. G Kandlikar studied "Fundamental issue related to flow boiling in minichannel and micro channels" Based on engineering practice and application areas employing these channels, Kandlikar proposed the following limits by hydraulic diameter: conventional channel (Dh larger than 3mm), mini-channel (Dh between 200µm and 3mm), micro-channel (Dh between 10 and 200µm).

Shizuo Saitoh et al.[P8] Studied "Correlation for boiling heat transfer of R-134a in horizontal tubes including effect of tube diameter" and the effect of tube diameter on flow boiling heat transfer coefficient was characterized by the Weber number in gas phase. Results showed that this correlation could be applied to a wide range of tube diameters (0.5–11-mm-ID). In addition, the dryout point and the heat transfer characteristics after the dryout point were also investigated based on the annular flow model. A modified Chen-type correlation for the flow boiling heat transfer was developed that included the effect of tube diameter. In this correlation, the effect of tube diameter on flow boiling heat transfer was characterized by the Weber number. The correlation agreed reasonably well with experimental data for a wide range of tube diameter from 0.51 to 10.92 mm ID. From this study of paper we conclude that the modified chen type correlation better suitable for least MAE compare to kandlikar correlation and gungor and winterton correlation.

Sung Min Kim et al[P9] Studied "Review of databases and predictive methods for heat transfer in condensing and boiling mini/micro-channel flows." He compared the correlation over large The accuracy of the universal correlation is also examined in by comparing individual mini/micro-channel databases from 26 sources with predictions of the universal correlation as well as select previous correlations that have shown relatively superior predictive capability. The universal correlation provides good predictions for all individual databases; with MAE least values indicating that their accuracy is not compromised against specific databases. With the most superior MAE the universal correlation predicts databases more accurately than by any of the select previous correlations. It is shown that, despite the success of previous predictive methods for specific fluids and narrow databases, this method are incapable of providing accurate predictions against entire databases. The databases are used to develop ‘universal’ correlations with very broad application range.

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Experimental Investigation on Boiling Heat Transfer using R134A (J4R/ Volume 02 / Issue 03 / 005)

Arijit Kundu et al.[P2] Studied "Heat transfer characteristics and flow pattern during two-phase flow boiling of R134a and R407C in a horizontal smooth tube." He carried out experiments to measure flow boiling heat transfer coefficients and pressure drops of R134a and R407Cinside a smooth horizontal tube (9.52 mm outside diameter, 1.2 m length) were performed at a refrigerant mass flux range of about 100–400 kg/m2 s varying the inlet temperature of the evaporator within the range of 5–9 C, with heat fluxes within the range 3–10 kW/m2 . He conclude that The heat transfer coefficients of pure fluid R134a are higher than that of refrigerant blend R407C for all mass velocities and heat fluxes and the difference increases with the increase in mass velocities and Also the local heat transfer coefficient increases for both the refrigerants before the dry-out occurs. The heat transfer coefficients of pure fluid R134a are higher than that of refrigerant blend R407C for all mass velocities at different flux and for R407C HTC is max at vapour quality between 0.3-0.4 and for R134a HTC is max at vapour quality between 0.7-0.8.

Zahid Anwar et al.[P4] studied "Flow boiling heat transfer, pressure drop and dryout characteristic of R1234yf: Experimental results and predictions" on Flow boiling heat transfer, pressure drop and dryout characteristics of R1234yf in a vertical stainless steel test section (1.60 mm inside diameter and 245 mm heated length) under upward flow conditions are reported in this article.

The experiments were carried out at 27 and 32 C saturation temperatures with five mass fluxes in the range of 100–500 kg/m2 s while the applied heat flux was in the range of 5–130 kW/m2 . He concludes that the boiling heat transfer was strongly controlled by the applied heat flux with insignificant effect of mass flux and vapour quality.

Fig. 1: Schematic diagram of set up

III. METHODOLOGY OF WORK A large number of correlations have been proposed. Most of them are based on data from a single source or from a few sources and do not perform outside the range of those data. There are some correlations which were originally based on a limited amount of data but have been compared by others with more data for many fluids with good results. Among such correlations are those of Lazarek and black, Agostini and Bontemps, Liu and Wu, Oh and Son and Tran et al.

Using the Boiling heat transfer correlations for annular flow and find its predicted heat transfer coefficient using Refprop-9.0 and thermodynamics equations. Also we know the experimentally heat transfer coefficient from Literature then find the MAD (mean absolute deviation).

Saturated flow boiling heat transfer correlation for mini/microchannel Lazarek and Black Correlation: h tp  ( 30 Re

0 . 857 fo

Bo

 kf )   Dh

0714

   

(1)

Agostini and Bontemps Correlation: htp  28 q H

'' 2 / 3

htp  28 q H

G

'' 2 / 3

 0 . 26

G

x

 0 . 64

 0 . 10

x

 2 . 08

for X < 0.43,

(2)

for X > 0.43

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Experimental Investigation on Boiling Heat Transfer using R134A (J4R/ Volume 02 / Issue 03 / 005)

Liu and Wu. Correlation: h tp  334 Bo

0 .3

( B d R ef )

kf

0 .4

Dh

(3)

Oh and Son Correlation: h tp  0 . 034 Re

0 .8 f

 1  0 .3  Pr f [1 . 58    x tt 

0 . 87

]

kf Dh

(4)

Tran et al. Correlation: h tp  8 . 4  10 ( Bo We 5

2

fo

)

0 .3

 g    f

   

0 .4

(5) Using above correlation and find the prediction boiling heat transfer coefficient. After finding the prediction boiling heat transfer coefficient value find the MAD (mean absolute deviation) value in percentage. Minimum value of MAD, that’s called Assessment of correlation for boiling heat transfer coefficient.

IV. RESULT AND DISCUSSION Results is consider for using refrigerant R134a for different mini channel circular 1.60, 0.64 2.00,.0.54,4.26,and 2.62 mini channel, saturation temperatures from 10 to 32, mass fluxes from 125 to 500 kg/m 2s and vapor qualities from 0.1 to 0.9.

The 217 experimental data as indicated in table 3.1 are used for the comparative study of the flow boiling heat transfer correlations as described above. The criterion used for evaluation is the mean absolute relative deviations (MAD). By the way, the mean relative deviations (MRD) is used to check whether a correlations has an over-prediction or under prediction in general.

MAD =

1 N

Sr No. 1.

2.

3.

4.

5.

∑N i=1 (

h(i)pred −h(i)exp h(i)exp

)

(6)

Table – 1 MAD for R134a Refrigerant for different Diameter Correlation Name Hydraulic Diameter (mm) Channel Type Liu and Wu. 1.60 Circular Agostini and Bontemps 1.60 Circular Lazarek and Black 1.60 Circular Tran et al.

1.60 Circular Oh and Son 1.60 Circular

MAD % 14.52 21.06 23.29 39.49 98.27

6.

7.

8.

9.

10.

Lazarek and Black Liu and Wu. Agostini and Bontemps Tran et al.

Oh and Son

0.64 0.64 0.64 0.64 0.64

Circular Circular Circular Circular Circular

12.38 22.90 39.78 45.65 96.04

11.

12.

13.

14.

15.

Tran et al.

Lazarek and Black Agostini and Bontemps Liu and Wu. Oh and Son

2.00 2.00 2.00 2.00 2.00

Circular Circular Circular Circular Circular

37.02 40.37 50.92 69.74 93.84

16.

17.

18.

19.

20.

Tran et al.

Lazarek and Black Liu and Wu. Agostini and Bontemps Oh and Son

0.54 0.54 0.54 0.54 0.54

Circular Circular Circular Circular Circular

37.07 49.81 80.03 96.89 98.00

21.

22.

23.

24.

25.

Tran et al.

Liu and Wu. Lazarek and Black Agostini and Bontemps Oh and Son

4.26 4.26 4.26 4.26 4.26

Circular Circular Circular Circular Circular

19.96 28.19 30.61 47.44 98.00

26.

27.

28.

Liu and Wu. Lazarek and Black Tran et al.

2.62 2.62 2.62

Circular Circular Circular

29.91 33.99 38.00

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Experimental Investigation on Boiling Heat Transfer using R134A (J4R/ Volume 02 / Issue 03 / 005)

29.

30.

Agostini and Bontemps Oh and Son

2.62 2.62

Circular Circular

50.03 95.26

V. CONCLUSION In present research we concluded that Lazerek and Black correlation is most suitable compare to other for mini channel and also Tran et al. also good prediction for 2.00, 0.54 and 4.26. The heat transfer coefficients of pure fluid R134a are higher than that of refrigerant blend R407C for all mass velocities at different flux and also conclude that The boiling heat transfer was strongly controlled by the applied heat flux with insignificant effect of mass flux and vapour quality.

NOMENCLATURE Q H Î&#x201D;T

Dh Ac P Bn G Ď D Đą Re Nu Pr G T P V I i iv l b A x

Amount of heat flux, w/m2 Heat transfer coefficient w/m2k Temperature differences between the solid surfaces and surrounding fluid area,k Hydraulic diameter (m) Surface area or cross section area (m2) Perimeter of shape Bond number Acceleration due to gravity density (kg/m3) Diameter of channel (m) Surface tension Reynold number Nusselt number Prandtl number Mass flux (kg/m2s) temperature (C) Pressure drop (bar) Heating voltage (V) Current (A) Specific enthalpy of standard (J/kg) Latent heat (J/kg) Effective heat transfer rate (W) Length of the square mini channel size (m) Cross sectional area of mini channel (m2) Vapour quality

Greek Symbols đ??&#x20AC;

Thermal conductivity (m)

Abbreviations HTC

Heat transfer coefficient

Subscripts C Exp i in l o Out Pre r s V

Cooling water Experimental Inside Inlet Liquid Outside Outlet Predicted Refrigerant Saturation Vapour

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Experimental Investigation on Boiling Heat Transfer using R134A (J4R/ Volume 02 / Issue 03 / 005)

W

wall

REFERENCES [1] [2] [3] [4] [5] [6] [7] [8]

http://getdata-graph-digitizer.com/download.php

https://www.irc.wise.edu/properties/ Yunus A. Cengel; 3rd; "Heat and mass Transfer", Page: 515-53 S.G Kandlikar "Fundamental issue related to flow boiling in minichannel and micro channels" [2002] Exp. Thermal Fluid Sci. 26, 389-407 Shizuo Saitoh et al.''Correlation for boiling heat transfer of R-134a in horizontal tubes including effect of tube diameter.'' [2007] International Journal of Heat and Mass Transfer 50 (2007) 5215–5225.

Sung Min kin et al. Review of databases and predictive methods for heat transfer in condensing and boiling mini/micro-channel flows [2014] Int journal of heat and mass transfer 47, 5749-5763 Arijit Kundu et al.'' Heat transfer characteristics and flow pattern during two-phase flow boiling of R134a and R407C in a horizontal smooth tube.'' [2014] Experimental Thermal and Fluid Science 57 (2014) 344–352 Zahid Anwar et al. ''Flow boiling heat transfer, pressure drop and dryout characteristic of R1234yf: Experimental results and predictions'' [2015] Experimental Thermal and Fluid Science 66 (2015) 137–149

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