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Numerical Investigation of heat transfer enhancement of SiO2-water based nanofluids in Light water nuclear reactor
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 4 (2017) 10118–10122
www.materialstoday.com/proceedings
ICEMS 2016
Numerical Investigation of heat transfer enhancement of SiO2-water based nanofluids in Light water nuclear reactor Deepak Sharmaa,*, K.M. Pandeya, Ajoy Debbarmaa, Gautam Choubeya a
Department of Mechanical Engineering, National Institute of Technology Silchar-788010,India
Abstract Nanofluid performed a very crucial role in nuclear power plant for improving heat transfer. Due to high thermal conductivity of nanofluid heat transfer capacity in nuclear reactor can be thousand times larger than conventional fluids like water. So the efficiency of nuclear reactor is improving and also reducing the thermal hydraulics problems. It opens a new gateway for gaining higher energy optimization. For improving the heat transfer in light water reactor, SiO2-water based nanofluids properties were used for numerical investigation. Heat transfer of nanofluid can be functions of volume concentration, physical properties and size of nanoparticles etc. Density, thermal conductivity, specific heat and viscosity were investigated and operated as a basic data for ANSYS 14. In this numerical investigation three value of weight concentration of nanoparticles in the range of 1%, 2% and 3% were used. A uniform heat flux is applied at the wall of annular rod. The numerical method which is available in CFD package of Ansys CFX 14 has been used here. Turbulence models of k–ω has been used in this numerical analysis. Validation of result has been done by analytical equations. Numerical investigation of various effect on characteristics of heat transfer in light water nuclear reactor by using SiO2-water based nanofluid is the key objective of the study. Coefficient of heat transfer and temperature of clad wall profiles are plotted without nanofluids and with nanofluids. © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS-2016). Keywords: Nanofluid; Convection; Turbulent Regime; Heat Transfer Enhancement.
1. Introduction From past few years cost of energy is rising very fast but demand of energy is also rising rapidly day by day. So for fulfilling the demand of energy new types of cooling fluid should be used for enhancing the efficiency of power generation. * Corresponding author. Tel.:+91-9411693618; Fax: 03842-224797 E-mail address: [email protected]
2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS2016).
Deepak Sharma/ Materials Today: Proceedings 4 (2017) 10118–10122
10119
New generation cooling fluids are nanofluids which are giving a better performance comparison to conventional fluids. Nanoparticles which are in nano size less than 100nm suspended in base fluid water for enhancing the heat carrying capacity of fluid [1]. Lot of experimental and numerical research has been done by using various mixtures of conventional fluid and metallic nanoparticles like copper, silver, titanium because of higher thermal conductivity. Lee et al. [2] found that by virtue of rise in thermal conductivity enhancement of heat carrying capacity takes place in laminar flow. This indicates that nanofluid flow is influenced by existence of particles and due to fluid particle interaction [3]. Water is suitable conventional fluid for mixing nanoparticles due to low volatility and lower freezing point. Various benefits of using nanofluids are enhancing the heat transfer, energy saving, clogging decrement, cooling in micro channel [4]. Cho and Pak [5] examined the performance characteristics of heat transfer in TiO2 nanofluids. Maiga et al. [6] performed numerical simulation on characteristics of heat transfer in Al2O3-water and Al2O3-EG nanofluids at uniform heat flux in heated tube. Numerical investigation of various effect on characteristics of heat transfer in light water nuclear reactor by using SiO2-water based nanofluid is the key purpose of this study. 2. Numerical Modeling In this numerical investigation VVER-440 type reactors is considered. The triangular configuration which is used for simulation consist one quarter rod part, eight complete fuel rods and four halved fuel rods. The total length of triangular pattern is 1m, rod inner and outer diameter are 9.1 and 7.57mm and pitch are 12.75mm respectively. In this numerical investigation, the nanofluid which is used as a coolant for flowing in the domain with velocity of 2.5m/s, coolant temperature at inlet is 298K. A uniform heat flux is kept at the inner wall of rod. The pressure is fixed as zero at the outlet. In present numerical investigation the k-ω SST turbulence model were used for discretizing the domain using finite volume technique. For good convergence and better accuracy in simulated results the top model is k-ω SST because it can predicted the flow in the wake of the sub channel very well. The governing equations which are using in this investigation are solved by using CFX. Various meshes of different element size has been tested and it is shown in Figure.1.
Fig. 1. (a). Geometry under investigation (b) Meshing of model in various sectional view
3. Governing Equations In this investigation for incompressible flow Navier Stokes equations can be written in the Cartesian coordinate which are given below: Mass conservation: .
0
1
10120
Deepak Sharma / Materials Today: Proceedings 4 (2017) 10118–10122
Momentum Conservation: .
2
Energy Conservation: .
.
,
.
3
4. Nanofluid Data Reduction Nanofluid properties are obtained by correlations which are given below: Density: ρ
1
ρ
ρ
4
Specific heat: ,
,
,
5
Viscosity: 1
2.5
Thermal Conductivity: 1
4.4
.
.
6 .
.
7
5. Validation Comparison of numerical result with the analytical result represent accurate and superior in nature. Wall adjacent temperature profiles can be seen in Figure. 2 at varying Reynolds number and 1% volume concentration is validated by analytical result and it is calculated from the formula approximately overlying with coming result from ANSYS CFX. 8
Fig. 2. Comparison of numerical and analytical result of temperature profile
Deepak Sharma/ Materials Today: Proceedings 4 (2017) 10118–10122
10121
6. Result and discussion The numerical investigated results of vertical triangular channel are calculated and presented in this section. Effect on heat transfer characteristics by using without nanofluid or with SiO2/water based nanofluid, are reported in this section. Figure. 3 shows the contours of wall adjacent temperature of clad, heat transfer coefficient and velocity contours.
Fig. 3. (a) Heat transfer coefficient contour (b) Wall adjacent temperature contour at Ø=1%
7. Consequences of varying weight concentration and Reynolds number on heat transfer characteristics Coefficient of heat transfer and clad temperature plots are given below in figure 4 for varying volume concentration and varying Reynolds number. As shown in figure 4 as the Reynolds number and volume concentration is increasing clad wall temperature decreases and coefficient of heat transfer is increasing due to varying inlet velocity of nanofluid. Coefficient of heat transfer is 16% more for 1% nanofluid concentration than pure water. Heat transfer enhancement is more when nanofluid concentration is less. When concentration is increasing from 1% to 2% coefficient of heat transfer is increasing but not more than that of 1% and temperature of clad wall also decreasing more for 1% volume concentration rather than other volume concentrations.
Fig. 4. (a) Heat transfer coefficient (b) Wall adjacent temperature at varying volume concentration with varying Reynolds Number
10122
Deepak Sharma / Materials Today: Proceedings 4 (2017) 10118–10122
8. Conclusion In this numerical investigation consequences of nanofluid properties on characteristics of heat transfer has been identified. It was observed from the simulation that the SiO2/water based nanofluid enhanced the heat transfer characteristic compared to the base fluid water. Various effects are obtained from this numerical investigations are: (1) Enhancement in heat transfer significantly increases after addition of SiO2 nanoparticles in base fluid compared to pure fluid. (2) Coefficient of heat transfer improved with varying particle concentration and with varying Reynolds number. From pure water to 1% the local heat transfer coefficient increases up to 24.6 %. (3) Temperature of clad wall is decreasing more for less volume concentration of nanofluid. References [1] Z.W. Xu, Design Strategies for optimizing high burn up Fuel in Pressurized Water Reactors, A Thesis for Doctor’s Degree in MIT, 2003. [2] K. S. Das, S.U.S Choi, Y. Wenhua, T. Pradeep, Nanofluids: Science and Technology. John Wiley & Sons, Inc. New Jersey, 2007. [3] K.B. Anoop, T. Sundararajan, K.S. Das, Int. J. of Heat and Mass Transf. 52 (2009) 2189–2195. [4] S.Z. Heris, M. N. Esfahany, G. Etemad 52 (2007) 1043–1058. [5] S.M. Fotukian, M.N. Esfahany, Int. J. of Heat and Fluid Flow 31 (2010) 606-612. [6] X.Q. Wang, A.S. Mujumdar, Int. J. Therm. Sci. 46 (2007) 1–19.
ScienceDirect Materials Today: Proceedings 4 (2017) 10118–10122
www.materialstoday.com/proceedings
ICEMS 2016
Numerical Investigation of heat transfer enhancement of SiO2-water based nanofluids in Light water nuclear reactor Deepak Sharmaa,*, K.M. Pandeya, Ajoy Debbarmaa, Gautam Choubeya a
Department of Mechanical Engineering, National Institute of Technology Silchar-788010,India
Abstract Nanofluid performed a very crucial role in nuclear power plant for improving heat transfer. Due to high thermal conductivity of nanofluid heat transfer capacity in nuclear reactor can be thousand times larger than conventional fluids like water. So the efficiency of nuclear reactor is improving and also reducing the thermal hydraulics problems. It opens a new gateway for gaining higher energy optimization. For improving the heat transfer in light water reactor, SiO2-water based nanofluids properties were used for numerical investigation. Heat transfer of nanofluid can be functions of volume concentration, physical properties and size of nanoparticles etc. Density, thermal conductivity, specific heat and viscosity were investigated and operated as a basic data for ANSYS 14. In this numerical investigation three value of weight concentration of nanoparticles in the range of 1%, 2% and 3% were used. A uniform heat flux is applied at the wall of annular rod. The numerical method which is available in CFD package of Ansys CFX 14 has been used here. Turbulence models of k–ω has been used in this numerical analysis. Validation of result has been done by analytical equations. Numerical investigation of various effect on characteristics of heat transfer in light water nuclear reactor by using SiO2-water based nanofluid is the key objective of the study. Coefficient of heat transfer and temperature of clad wall profiles are plotted without nanofluids and with nanofluids. © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS-2016). Keywords: Nanofluid; Convection; Turbulent Regime; Heat Transfer Enhancement.
1. Introduction From past few years cost of energy is rising very fast but demand of energy is also rising rapidly day by day. So for fulfilling the demand of energy new types of cooling fluid should be used for enhancing the efficiency of power generation. * Corresponding author. Tel.:+91-9411693618; Fax: 03842-224797 E-mail address: [email protected]
2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS2016).
Deepak Sharma/ Materials Today: Proceedings 4 (2017) 10118–10122
10119
New generation cooling fluids are nanofluids which are giving a better performance comparison to conventional fluids. Nanoparticles which are in nano size less than 100nm suspended in base fluid water for enhancing the heat carrying capacity of fluid [1]. Lot of experimental and numerical research has been done by using various mixtures of conventional fluid and metallic nanoparticles like copper, silver, titanium because of higher thermal conductivity. Lee et al. [2] found that by virtue of rise in thermal conductivity enhancement of heat carrying capacity takes place in laminar flow. This indicates that nanofluid flow is influenced by existence of particles and due to fluid particle interaction [3]. Water is suitable conventional fluid for mixing nanoparticles due to low volatility and lower freezing point. Various benefits of using nanofluids are enhancing the heat transfer, energy saving, clogging decrement, cooling in micro channel [4]. Cho and Pak [5] examined the performance characteristics of heat transfer in TiO2 nanofluids. Maiga et al. [6] performed numerical simulation on characteristics of heat transfer in Al2O3-water and Al2O3-EG nanofluids at uniform heat flux in heated tube. Numerical investigation of various effect on characteristics of heat transfer in light water nuclear reactor by using SiO2-water based nanofluid is the key purpose of this study. 2. Numerical Modeling In this numerical investigation VVER-440 type reactors is considered. The triangular configuration which is used for simulation consist one quarter rod part, eight complete fuel rods and four halved fuel rods. The total length of triangular pattern is 1m, rod inner and outer diameter are 9.1 and 7.57mm and pitch are 12.75mm respectively. In this numerical investigation, the nanofluid which is used as a coolant for flowing in the domain with velocity of 2.5m/s, coolant temperature at inlet is 298K. A uniform heat flux is kept at the inner wall of rod. The pressure is fixed as zero at the outlet. In present numerical investigation the k-ω SST turbulence model were used for discretizing the domain using finite volume technique. For good convergence and better accuracy in simulated results the top model is k-ω SST because it can predicted the flow in the wake of the sub channel very well. The governing equations which are using in this investigation are solved by using CFX. Various meshes of different element size has been tested and it is shown in Figure.1.
Fig. 1. (a). Geometry under investigation (b) Meshing of model in various sectional view
3. Governing Equations In this investigation for incompressible flow Navier Stokes equations can be written in the Cartesian coordinate which are given below: Mass conservation: .
0
1
10120
Deepak Sharma / Materials Today: Proceedings 4 (2017) 10118–10122
Momentum Conservation: .
2
Energy Conservation: .
.
,
.
3
4. Nanofluid Data Reduction Nanofluid properties are obtained by correlations which are given below: Density: ρ
1
ρ
ρ
4
Specific heat: ,
,
,
5
Viscosity: 1
2.5
Thermal Conductivity: 1
4.4
.
.
6 .
.
7
5. Validation Comparison of numerical result with the analytical result represent accurate and superior in nature. Wall adjacent temperature profiles can be seen in Figure. 2 at varying Reynolds number and 1% volume concentration is validated by analytical result and it is calculated from the formula approximately overlying with coming result from ANSYS CFX. 8
Fig. 2. Comparison of numerical and analytical result of temperature profile
Deepak Sharma/ Materials Today: Proceedings 4 (2017) 10118–10122
10121
6. Result and discussion The numerical investigated results of vertical triangular channel are calculated and presented in this section. Effect on heat transfer characteristics by using without nanofluid or with SiO2/water based nanofluid, are reported in this section. Figure. 3 shows the contours of wall adjacent temperature of clad, heat transfer coefficient and velocity contours.
Fig. 3. (a) Heat transfer coefficient contour (b) Wall adjacent temperature contour at Ø=1%
7. Consequences of varying weight concentration and Reynolds number on heat transfer characteristics Coefficient of heat transfer and clad temperature plots are given below in figure 4 for varying volume concentration and varying Reynolds number. As shown in figure 4 as the Reynolds number and volume concentration is increasing clad wall temperature decreases and coefficient of heat transfer is increasing due to varying inlet velocity of nanofluid. Coefficient of heat transfer is 16% more for 1% nanofluid concentration than pure water. Heat transfer enhancement is more when nanofluid concentration is less. When concentration is increasing from 1% to 2% coefficient of heat transfer is increasing but not more than that of 1% and temperature of clad wall also decreasing more for 1% volume concentration rather than other volume concentrations.
Fig. 4. (a) Heat transfer coefficient (b) Wall adjacent temperature at varying volume concentration with varying Reynolds Number
10122
Deepak Sharma / Materials Today: Proceedings 4 (2017) 10118–10122
8. Conclusion In this numerical investigation consequences of nanofluid properties on characteristics of heat transfer has been identified. It was observed from the simulation that the SiO2/water based nanofluid enhanced the heat transfer characteristic compared to the base fluid water. Various effects are obtained from this numerical investigations are: (1) Enhancement in heat transfer significantly increases after addition of SiO2 nanoparticles in base fluid compared to pure fluid. (2) Coefficient of heat transfer improved with varying particle concentration and with varying Reynolds number. From pure water to 1% the local heat transfer coefficient increases up to 24.6 %. (3) Temperature of clad wall is decreasing more for less volume concentration of nanofluid. References [1] Z.W. Xu, Design Strategies for optimizing high burn up Fuel in Pressurized Water Reactors, A Thesis for Doctor’s Degree in MIT, 2003. [2] K. S. Das, S.U.S Choi, Y. Wenhua, T. Pradeep, Nanofluids: Science and Technology. John Wiley & Sons, Inc. New Jersey, 2007. [3] K.B. Anoop, T. Sundararajan, K.S. Das, Int. J. of Heat and Mass Transf. 52 (2009) 2189–2195. [4] S.Z. Heris, M. N. Esfahany, G. Etemad 52 (2007) 1043–1058. [5] S.M. Fotukian, M.N. Esfahany, Int. J. of Heat and Fluid Flow 31 (2010) 606-612. [6] X.Q. Wang, A.S. Mujumdar, Int. J. Therm. Sci. 46 (2007) 1–19.