1 room 3 rc tuesday, 9 february 2010 - program studi ... · tuesday, 9 february 2010 1 rc me ae...

Room 3 Tuesday, 9 February 2010

RCMeAe

SESSION 1Energy System10.30 - 12.00

Paper Code :111Title :State of the Art on Sorption Refrigeration: a Challenge and Prospect

Author :I Made Astina

Paper Code :219Title :

Author :

Thermal and Flow Characteristics of Water Based Mixture of Coconut Oil and Rich Mixture to be used as Secondary Refrigerant in Air Conditioning System

Y.S. Indartono, H. Usui, H. Suzuki, Y. Komoda, D. Mujahidin

FAME

Paper Code :110Title :Design and Non-Isentropic Performance Simulation of an Ejector Refrigeration

System Powered by Engine Coolant Water

Author :C. Meng, I M. Astina, P. S. Darmanto, H. Sato

Paper Code :122Title :Analytical Study Of The Transport Properties In Different Refrigerants That

Influence The Performance Of An Organic Rankine CycleAuthor :Prabowo, Mika Patayang, Meshack Otedo O.

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Room 3 Tuesday, 9 February 2010

RCMeAe


Paper Code :201Title :A Study Of Performance Of Engine Running On Bio Ethanol Fuel And It's

Effect On A Four Stroke Engine ComponentsAuthor :Yusuf Siahaya, Yustinus Edward K.M.

Paper Code :211Title :Influence of Injection Timing on Performance and Combustion of an IDI

engine fuelled with DME

Author :Kanit Wattanavichien

Paper Code :112Title :CFD Assessment of a Combined Ejector Performance Analysis Method

Applied with HCs Working Fluid

Author :S. Chan, A. Suwono, I M. Astina, P. S. Darmanto, H. Sato

Paper Code :215Title :Thermal Engineering Performance Evaluation of a Polymer Electrolyte

Membrane Fuel Cell Stack at Partial LoadAuthor :W.A.Najmi W.M., Rahim A. , M. Fairuz. R

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Room 3 Wednesday, 10 February 2010

About RC-MeAe 2010

Table of Contents

Schedule

Keynote Lectures

Paper List

Author List

RCMeAe


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Paper Code :220Title :Experimental Study on the Natural Convection Characteristic of AP1000 Passive

Containment Cooling SystemAuthor :Ari Darmawan Pasek, Yerri N. Kartiko, Daddy Setyawan, Efrison Umar, Aryadi Suwono

Paper Code :139Title :Optimization of Liquid Cooling System of Desktop Computer Through

Computational Fluid Dynamic Simulation

Author :M. Hamdi, W.J Loh, N. Farhanah

Paper Code :136Title :Investigation of higher cooling capacity PC processor heat sink Author :Abdurrachim H., Sutrisno

Paper Code :137Title :Study Of Heat Transfer In A Multihole Plate. Application For Cooling Combustor

Walls And Turbine Blades Of TurbomachineryAuthor :Nguyen Phu Hung, Eva Dorignac

Paper Code :114Title :Numerical Study of Natural Convection Air Cooling of a PEFC: Single Cell and

StackAuthor :A.P. Sasmito, E. Birgersson, K.W. Lum, A.S. Mujumdar

Paper Code :217Title :Simulation Analysis of 2 Stages CO2 Heat Pump Water Heater

Author :Pramote Laipradit, Wimonnad Charote, Kusuma Suntornprasert, Khanida Koupratoom

Room 3 Wednesday, 10 February 2010

RCMeAe


Paper Code :202Title :Mathematical Modelling of Combustion Rate Using Carbon Deposit On a Wastes

Bubbling Fluidized Bed ReactorAuthor :I Nyoman Suprapta Winaya

Paper Code :223Title :

Author :Yatna Yuwana Martawirya,Nathanael Panagung Tandian, Aries Karyadi

Preliminary Study Of Web-based Software Of Information System And Simulation For Components Of Kamojang Geothermal Power Plant

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Paper Code :221Title :Upgrading of Municipal Solid Waste as Solid Fuel to Subbituminous Coal Grade

by Torrefaction ProcessAuthor :Toto Hardianto, Amrul, Aryadi Suwono, Ari Darmawan Pasek

Paper Code :207Title :Design and Simulation of Combustor for Turbocharger Based Micro Gas Turbine

System Using LPG and BiogasAuthor :T. A. Fauzi Soelaiman, N. P. Tandian, R. Febrianda

Paper Code :334Title :Early Design Optimization In Hot Briquetting MachineAuthor :Asep Indra Komara, I Wayan Suweca

Paper Code :209

Title :Application of ejectors to closed-cycle OTEC and SOTEC powerplantsAuthor :Menandro Serrano Berana and Masafumi Nakagawa

Regional Conference on Mechanical and Aerospace Technology

Bali, February 9 – 10, 2010

112-1

CFD Assessment of a Combined Ejector Performance

Analysis Method Applied with HCs Working Fluid

Sarin Chan

(a,c), Aryadi Suwono

(a), I Made Astina

(a), Prihadi Setyo Darmanto

(a) ,

Haruki Sato(b)

(a) Mechanical Engineering Dept., Faculty of Mechanical and

Aerospace Engineering, Institut Teknologi Bandung,

Jl. Ganesha No. 10, Bandung 40132 INDONESIA

Tel: (62-22) 250 6447, Fax: (62-22) 253 4099

(b) Faculty of Science and Technology, Keio University,

3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522 JAPAN

Tel/Fax: (81-45) 566-1729, E-mail: [email protected]

(c) Mechanical and Industrial Dept, Institute of Technology of Cambodia,

Pochentong Boulevard, P.O. Box 86, Phnom Penh, CAMBODIA

E-mail: [email protected]

Abstract : This paper presents the results of using CFD method to study the

performance of an actual ejector operated with Propane. Referred to the CFD results, the

combined theoretical method is assessed. The absence of normal shock wave predicted by

the combined theoretical method is confirmed by CFD results. It is pointed out that the

efficiency values included by the theoretical method depend on fluid type and ejector

design. The combined theoretical method would be used in the preliminary studies of the

system performance with respect to large or new working candidates and wide range of

operating conditions. CFD studies would then be used to optimize the ejector design and

anticipate or troubleshoot the problems of the ejector.

Keywords : ejector, CFD, combined theoretical method, performance analysis

1. Introduction

A method based on a combination between

constant-area-ejector mixing theory and the so-

called shock-circle definition has been

implemented by our group in the analysis of

ejector refrigeration system [1,2]. The calculated

results are found to have good agreement with the

reported available experimental data of R-141b

and R-11, for both entrainment and compression

ratios. The method has been used in our previous

works to study the performance of simple and

novel ejector refrigeration cycles with various

HCs refrigerants. Interesting results suggest that

Propane appear to be the best refrigerant

especially for heat source temperatures lower than

95oC. As the method utilizes some empirical

constants, the calculation results must be assessed

when studying the fluid differed from the original

fluid when the method was being developed.

Available literatures reported the capability of

CFD analysis in dealing with the complex flows

inside ejector and providing good overall

performance prediction in all operating modes of

ejector [3-7]. The CFD method also takes into

account the complex effects of physical geometry

of ejector.

Zhu, et al. [3] established CFD models of their

actual ejector working with R-141b and

performed validation of the models with the

testing data. Three turbulent models were tested

and the results show that “RNG k- model” is the

best one describing the experimental data with

only 9.29% of maximum deviation. Seven data

points of different operating conditions were

compared. The authors also report the effects of

mixing section converging angle and the nozzle

exit position on the ejector performance based on

their extensive CFD testing results. The

comparisons of the CFD and the experiments of

supersonic air ejector were carried out by Hemidi,

et al. [8]. Good prediction of the entrainment

ratios by CFD calculation was confirmed and the

overall deviation was less than 10% for k- model.



112-2

The inconsistency of local flow feature of

different turbulent models was observed, however

the ejector performance indicator, entrainment

ratio, was still well reproduced. The studies on

steam ejectors were reported by some researchers

[9, 6, 10]. Based on the independent comparisons

with their respective measurements data, CFD

analysis is confirmed to be a reliable tool for

studying and troubleshooting the ejector

performance. The CFD method was also tested

with other fluids like R-141b and methanol.

Rusly, et al. [7] studied the performance of four

ejectors of Haung, et al. [11], using CFD

technique and they found that errors of calculated

entrainment ratio are less than 10%. Riffat, et al.

[12] reported their experimental results and the

CFD analysis for the ejector working with

methanol.

Due to the lack of experimental data, CFD

analysis will be used in this study to assess the

reliability of the combined theoretical method of

constant-area mixing theory and the shock-circle

definition, applied for hydrocarbons (HCs) as

working fluids.

2. Combined Theoretical Method

The schematic of an ejector which is the main and

dominating component in the ejector refrigeration

cycle is shown in Fig. 1. The high-pressure vapor

known as primary fluid is expanded through

converging-diverging nozzle where its pressure

energy is converted into kinetic energy. The flow

leaving the nozzle with supersonic velocity and

very low pressure, provoke the entrainment of

secondary fluid from suction chamber. In the

constant-area section, the two flows mix and then

the mixed flow may experience succession

shockwaves at the end of constant area section

depending on the flow condition and the

geometrical design of ejector. Finally, the mixed

flow is further decelerated in the diffuser and

pressure is further recovered after some pressure

recovery has happened in the constant area

section. In the unfavorable design, the normal

shockwave may happen in the diffuser.

To simplify the complex flow phenomena

happened inside the ejector, the following

assumptions are made:

1. The flows are one-dimensional (except at

first interaction section A-A),

compressible and steady inside adiabatic

wall

2. The flow velocities at the inlet of primary

nozzle and suction chamber; and at the

outlet of diffuser, are considered

negligible

3. Constant coefficients are used to account

for the losses

4. The primary and secondary fluids are

completely mixed at the end of constant-

area section.

Primary

flow

Constant area

sectionDiffuser

Secondary

flow

Discharged

mixed flow

A

A

Suction

chamber

Dpm

Dt

Dcax

r

Figure 1. Schematic Diagram of Ejector

Based on the assumptions, the analytical

equations derived from mass, momentum and

energy balances are determined for solving the

flow problem. The constant-area-ejector theory

describes the mixing of primary jet flow from the

nozzle and entrained secondary flow, as

undergone inside constant cross sectional tube.

Incorporating the mixing theory with the so-called

shock-circle definition by [13] which prescribes

the conditions at the mixing starting point, section

A-A, the coupled equations can be solved to

determine the ejector entrainment ratio and the

thermodynamic state at the discharged of ejector.

The detail information on the combined

theoretical method can be found in our previous

reports [2, 1].

3. Ejector Design

An actual ejector have been designed and

manufactured for the experimental study on the

performance of ejector refrigeration system. The

dimensions of the main ejector parts, including

nozzle throat diameter and the constant-area

section diameter were determined by our

combined analysis method. The input parameters

are the required cooling capacity and the design

operating condition. Other physical dimensions of

the ejector were chosen based on the survey of the

existing ejectors reported in available literatures.



112-3

The ejector has movable nozzle and the position

of the nozzle can be altered even the system is in

operation. The ejector was designed for Propane

at the operating condition of Tg=70oC, Tc=35

oC

and Te=5oC. The efficiency values used in the

calculation with the combined method are 0.95 for

primary nozzle, 1 for suction nozzle, 0.82 for

effective expended flow, 0.92 for constant-area

mixing section and 0.95 for the diffuser. The

above efficiency values were obtained from

experimental data of reference [11] which can be

reproduced by our combined analysis method

with relative error within 15% for entrainment

ratios and 5% for critical discharged temperature.

Figure 2. Actual Ejector Design

4. CFD Modeling

The ejector shown in Fig. 2 is modeled as 2D

asymmetric problem. The CFD commercial

package, including grid generator, Gambit 2.3 and

solver, Fluent 6.3, are used in this study. There are

approximately 46000 elements of structured

quadrilateral meshes used on the ejector model.

The grids are at highest density in the jet entrained

zone which is between nozzle outlet and the inlet

of constant-area section. The grid structure of

ejector model is shown in Fig. 3.

The pressure-based implicit solver is selected in

Fluent. The renormalization group (RNG) k-

turbulent model is applied with standard near wall

treatment. Pressure inlet is used for boundary

conditions of both primary and secondary fluids

inlets. For the ejector discharged condition,

pressure outlet boundary condition is used.

Density of fluid is assumed as ideal gas while

other fluid properties use temperature dependent

polynomial functions which were fitted to data

calculated from real-gas equation.

5. Results and Discussion

Figure 4 shows the COPs of simple ejector cycle

with different HCs. The results were calculated by

the combined theoretical analysis method with the

same values of efficiencies given in the previous

section. The calculated results are independent of

ejector size. According to the figure, among all

studied HCs fluids, Propane provides the highest

COP.

0

0.1

0.2

0.3

0.4

0.5C

OP

Tg= 80oC

Tc= 35oC

Te= 10oC

Figure 4. COPs of Simple Ejector Cycle with

Different HCs Working Fluids

The performance of Propane predicted by the

combined analysis method is very convincing, as

good COP can be achieved under low generator

temperature heat source. However, the results

could be misleading due to the fact that the

combined theoretical method uses the efficiency

values that were derived exclusively from data of

R-141b. Therefore, CFD analysis will be used to

assess the combined theoretical method for the

case of Propane.



112-4

GridFLUENT 6.3 (axi, dbns imp, ske)

Jan 25, 2010

Figure 3. Grid arrangement of ejector model

The size of ejector including nozzle and constant-

area section diameters are provided as input data

to the combined analysis method along with the

generator and evaporator temperatures. With this

input set, the entrainment ratio and the critical

back pressure are calculated. It should be notified

that the theoretical analysis method can only

calculate ejector performance parameters at the

critical point.

Contours of Mach NumberFLUENT 6.3 (axi, pbns, rngke)

Jan 26, 2010

2.12e+00

2.03e+00

1.95e+00

1.87e+00

1.79e+00

1.71e+00

1.63e+00

1.55e+00

1.46e+00

1.38e+00

1.30e+00

1.22e+00

1.14e+00

1.06e+00

9.76e-01

8.95e-01

8.14e-01

7.32e-01

6.51e-01

5.70e-01

4.88e-01

4.07e-01

3.25e-01

2.44e-01

1.63e-01

8.14e-02

6.15e-05

Figure 5. Contours of Mach number for Ejector

Operated at Critical Discharged Pressure

0

0.5

1

1.5

2

2.5

0 50 100 150 200

Ma

ch N

um

ber

Axial Position, mm

Figure 6. Mach number along the Center Line of

Ejector Operated at Critical Discharged Pressure

0

0.2

0.4

0.8 1 1.2 1.4 1.6 1.8E

ntr

ain

men

t R

ati

o

Ejector Discharged Pressure, MPa

Tg= 60oC

Tg= 70oC

Tg= 80oC

Te= 10oC

Figure 7. CFD results for Ejector Performance

According to Figs. 5 and 6, there are successive

shock waves occurring after the primary fluid

leaving the nozzle, however there is no normal

shock wave at the exit of constant-area section.

This behavior agrees well with the prediction of

the combined theoretical method.

Figure 7 shows the CFD results of the ejector

performance worked with Propane. Differed from

theoretical method, CFD can calculate the

performance of ejector in all operating modes.

This is an advantage of the numerical method

compared to the analytical approach.

The critical entrainment ratios and discharged

pressures of ejector for generator temperatures of

60, 70 and 80oC, and for evaporator temperature

of 10oC, resulted from the CFD analysis are listed

in Table 1.

The calculation results from the combined

theoretical analysis method are also listed in Table

1. The data of entrainment ratios from CFD and

the combined theoretical method have very

different values. In case of critical discharged

pressure, the calculated results from the two

methods are in better agreement.

Table 1. Calculated data of Ejector Critical

Entrainment Ratio and Discharged Pressure



112-5

Tg

[oC]

CFD Combined

Theoretical Method

µ Pc*

[MPa]

µ Pc*

[MPa]

60 0.31 1.053 0.49 1.119

70 0.26 1.277 0.33 1.283

80 0.16 1.569 0.20 1.483

Better agreement of the calculated entrainment

ratios from CFD and the combined theoretical

methods can be achieved by changing the

efficiency values used in the combined analysis

method. Based on the results, it confirms that the

efficiency values derived from the experimental

data of R-141b ejectors would not valid for all

working fluids and ejectors. Besides working

fluid, the ejector design also contributes to the

value of efficiencies.

6. Conclusion

The CFD model of an actual ejector have been

created and analyzed to determine the

performance parameters including critical

entrainment ratio and discharged pressure of the

ejector. The CFD results of the ejector worked

with Propane are used to assess the combined

theoretical method. Concerning to the flow

situation at the exit of constant-area section when

the ejector operated at critical discharged

pressure, the combined theoretical method well

predicts that there is no normal shock as the flow

is already subsonic. This behavior is confirmed by

the CFD results. The theoretical method has

strong dependency on the values of efficiency

used for representing the losses occurred in the

components of ejector. The efficiency values

should be different for different working fluid and

ejector design. More rational values of the

efficiencies with respect to fluid in use and ejector

design are required. Because CFD analysis is very

time consuming, the reliable theoretical analysis

method should be used in the preliminary studies

of ejector system performances with large amount

of working fluids and operating conditions to

narrow down the working fluids candidates and

good operating conditions. The CFD should be

applied to have better performance prediction

incorporating with the effects geometric

parameters which are vital for the actual ejector

design.

Acknowledgement

The authors are grateful to the AUN/SEED-net

program and the Global COE program of Keio

University for supporting this study.

References

[1]. S. Chan , H. Sato, A. Suwono, I. M. Astina, P.

S. Darmanto, “Ejector-based refrigeration

cycle using HCs as the working fluid”. 8th

IIR Gustav Lorentzen Conference on Natural

Working Fluids 2008. Copenhagen, 2008

[2]. S. Chan, T. Takashi, H. Sato, A. Suwono,

“Feasibility Study on the Ejector-based

Cooling System using Natural Refrigerants”.

18th Environmental Engineering Symposium

2008, Tokyo, 2008.

[3]. Y. Zhu, W. Cai, C. Wen, Y. Li, “Numerical

investigation of geometry parameters for

design of high performance ejectors”.

Applied Thermal Engineering, Vol. 29, pp.

898-905, 2009

[4]. S. Varga, C. A. Oliveira, B. Diaconu,

“Numerical assessment of steam ejector

efficiencies using CFD”., International

Journal of Refrigeration, p. doi:10.1016/

j.ijrefrig.2009.01.007, 2009

[5]. S. Varga, C. A. Oliveira, B. Diaconu,

“Influence of geometrical factors on steam

ejector performance – a numerical

assessment”., International Journal of

Refrigeration, p. doi:10.1016/ j.ijrefrig.

2009.05.009, 2009

[6]. T. Utomo, M. K. Ji, H. S. Chung, H. M.

Jeong, S. H. Kwon, Y. S. Shin, “A CFD

Analysis on the Ejector Performance of Solar

MED-TVC”. 3rd International Solar Cities

Congress 2008. pp. 267-273, 2008

[7]. E. Rusly, L. Aye, W. Charters, A. Ooi, “CFD

analysis of ejector in a combined ejector

cooling system”., International Journal of

Refrigeration, Vol. 28, pp. 1092-1101, 2005

[8]. A. Hemidi, F. Henry, S. Leclaire, J.-M.,

Seynhaeve, Y. Bartosiewicz, “CFD analysis

of a supersonic air ejector. Part I:

Experimental validation of single-phase and

two-phase operation”., Applied Thermal

Engineering, Vol. 29, pp. 1523-1531, 2009

[9]. K. Pianthong, W. Seehanam, M. Behnia, T.

Sriveerakul, S. Aphornratana, “Investigation

and improvement of ejector refrigeration



112-6

system using computational fluid dynamics

technique”., Energy Conversion and

Management, Vol. 48, pp. 2556-2564, 2007

[10]. Y. Bartosiewicz, Z. Aidoun, Y. Mercadier,

“Numerical assessment of ejector operation

for refrigeration applications based on

CFD”., Applied Thermal Engineering, Vol.

26, pp. 604-612, 2006

[11]. B. Haung, J. Chang, C. Wang, V. Petrenko,

“A 1-D analysis of ejector performance”.,

International Journal of Refrigeration, Vol.

22, pp. 354-364, 1999

[12]. S. B. Riffat, S. A. Omer, “CFD modelling

and experimental investigation of an ejector

refrigeration system using methanol as the

working”. 2001, International Journal of

Energy Research, Vol. 25, pp. 115-128.

[13]. Y. Zhu, W. Cai, C. Wen, Y. Li, “Shock

circle model for ejector performance

evaluation”., Energy Conversion and

Management, Vol. 48, pp. 2533-2541, 2007

[14]. S. B. Riffat, G. Gan, S. Smith,

“Computational fluid dynamics applied to

ejector heat pumps”., Applied Thermal

Engineering, Vol. 16, pp. 291-297, 1996

[15]. A. Hemidi, F. Henry, S. Leclaire, J.-M.,

Seynhaeve, Y. Bartosiewicz, “CFD analysis

of a supersonic air ejector. Part II: Relation

between global operation and local flow

features”., Applied Thermal Engineering, p.

doi:10.1016/ j.applthermaleng. 2009.03.019,

2009

[16]. Y. Bartosiewicz, Z. Aidoun, P. Desevaux, Y.

Mercadier, “Numerical and experimental

investigations on supersonic ejectors”.,

International Journal of Heat and Fluid Flow,

Vol. 26, pp. 56-70, 2005

[17]. S. Balamurugan, V. G. Gaikar, A.W.

Patwardhan, “Effect of ejector configuration

on hydrodynamic characteristics of Gas-

liquid ejectors”., Chemical Engineering

Science, p. doi:10.1016/j.ces.2007.10.002,

2007

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