Effect of thermal energy storage layer porosity on performance of solar chimney power plant considering turbine pressure drop

Journal Pre-proof Effect of Thermal Energy Storage Layer Porosity on Performance of Solar Chimney Power Plant Considering Turbine Pressure Drop

Ali Asghar Sedighi, Zeynab Deldoost, Bahram Mahjoob Karambasti PII:

S0360-5442(19)32554-X

DOI:

https://doi.org/10.1016/j.energy.2019.116859

Reference:

EGY 116859

To appear in:

Energy

Received Date:

14 June 2019

Accepted Date:

24 December 2019

Please cite this article as: Ali Asghar Sedighi, Zeynab Deldoost, Bahram Mahjoob Karambasti, Effect of Thermal Energy Storage Layer Porosity on Performance of Solar Chimney Power Plant Considering Turbine Pressure Drop, Energy (2019), https://doi.org/10.1016/j.energy.2019.116859

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Journal Pre-proof Effect of Thermal Energy Storage Layer Porosity on Performance of Solar Chimney Power Plant Considering Turbine Pressure Drop Ali Asghar Sedighia,*, Zeynab Deldoostb, Bahram Mahjoob Karambastic a. Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran b. Faculty of new Sciences and Technologies, University of Tehran, Tehran, Iran c. Department of Mechanical Engineering, University of Guilan, Guilan, Iran Abstract: Performance of a solar chimney power plant (SCPP) is numerically investigated under the effects of turbine pressure drop, solar radiation and energy storage layer porosity. The solar chimney can be constructed on the soil with various properties and porosities as energy storage layer. In this article, the effects of soil porosity on the output power and energy efficiency of SCPP are investigated to find an appropriate porosity of soli. The results show that the output power of SCPP for each solar radiation and soil porosity becomes maximum at the optimum value of the turbine pressure drop. The efficiency of SCPP decreases and the output power of turbine increases with the increase in radiation flux. The reduction in efficiency compared to the increase in output power is negligible. In terms of energy efficiency and output power, the land with less porosity and the location with the high radiation is chosen as the most suitable place for construction of solar chimney power plant. Investigation of exergy loss from solar chimney outlet demonstrates that it is an increasing function of solar radiation and decreasing function of turbine pressure drop and soil porosity. Keywords: Solar Chimney Power Plant; Energy Storage; Porous Media; CFD; Exergy Analysis.

Nomenclature P

Pressure (pa)

V

Magnitude of velocity (m/s)

ρ

Density (kg/m3)

u

Velocity in x direction (m/s)

v

Velocity in y direction (m/s)

μ

Viscosity (kg/m.s)

g

Gravity (m/s2)

Β

Thermal expansion coefficient (1/K)

T

Temperature (K)

C

Heat capacity (j/kg.K)

λ

Thermal conductivity (W/m.K)

k

Turbulent kinetic energy (m2/s2)

ε

Turbulent dissipation rate(m2/s3)

μt

Turbulent viscosity (kg/m.s)

σt

Turbulent Prandtl number -1-

Journal Pre-proof Gk

Generation of turbulent kinetic energy due to the velocity gradient (kg/m.s3)

Gb

generation of turbulence kinetic energy due to the buoyancy (kg/m.s3)

σε

Turbulent dissipation rate Prandtl number

C1ε, C2ε, C3ε

Constants

φ

Porosity

K

Permeability (m2)

CF

Inertial coefficient

ma

Mass flow rate of the air at the outlet of the chimney (kg/s)

h

Enthalpy of air at the chimney outlet (kJ/kg)

s

Entropy of air at the chimney outlet (kJ/(kg.K))

T0

reference temperature (ambient temperature) (K)

h0

Enthalpy of air at the reference temperature (kg/s)

s0

Entropy of air at the reference temperature (kJ/kg)

η

Energy efficiency

Wt

Output power of turbine (W)

E

Solar radiation (W)

Subscripts 1

Parameters in the chimney

2

Parameters in the energy storage layer

1- Introduction Due to the increasing of energy consumption in the resent years, the problem of air pollution and the limitation of fossil fuel sources have been under consideration. Comprehensive studies were done to reduce the adverse effects of the emitted pollutants [1] and increase the efficiency of fossil fuel equipment such as heat exchangers [2]. Another way to meet the energy demand of consumers without polluting the air is using new energy sources such as solar radiation. By applying solar radiation, the air pollution will be controlled and the use of the limited sources of the fossil fuel will be reduced. The solar chimney power plant (SCPP) is used for generation of electricity from solar radiation which was investigated by Haaf et al. [3] and Haaf [4]. The SCPP were studied experimentally [5] and numerically [6] in the literature. The performance of SCPP was examined under the effects of the turbine speed, the number of turbine blades, the diameter of collector and the height of chimney [7], collector radius and height, chimney radius and height, and heat flux [8], slope of collector and chimney diverging angle [9], collector roof height [10], and strong ambient crosswind and low solar radiation [11]. Studies on the effect of the different parameters on the flow and heat transfer characteristics of air in a solar chimney make it possible to optimize the performance of SCPP. Gholamalizadeh and Kim [12] performed a simultaneous optimization of the total efficiency, output power, and expenditure to obtain the best collector radius, chimney radius, and chimney height. The most appropriate configuration of SCPP was found for -2-

Journal Pre-proof Kerman power plant and Manzanares prototype power plant. Gholamalizadeh and Kim [13] performed a thermo-economical optimization of SCPP efficiency, output power and expenditure to obtain the best combination of the geometrical parameters such as inlet height and outlet height of the collector, collector radius, and height and diameter of chimney. The optimal values of the collector inlet and outlet heights in the Kerman power plant were 1.5 m and 2.95 m, respectively. Those in the Manzanares power plant were obtained as 1.5 m and 4.6 m, respectively. Najm and Shaaban [14] investigated the effects of the turbine pressure drop, solar radiation and collector radius on the output power of SCPP. They found that the output power of solar chimney with the turbine pressure drop of 160 pa became maximum at solar radiation of 500 W/m2 where the collector radius was chosen 17 times the radius of chimney. A SCPP can be coupled with an energy storage device to produce uninterrupted power. The flow and heat transfer of fluid in energy storage system under the effects of various parameters was investigated in detail by many authors [15-17]. Several investigations were done on the performance of a SCPP coupled with energy storage systems [18-21]. Fadaei et al. [22] measured temperature and velocity to study the SCPP performance. Two kinds of experiments with and without heat storage system were carried out where the phase change material was selected as the energy storage. The results indicated that the use of energy storage system caused to increase the mass flow rate of the air in the chimney. Fadaei et al. [23] investigated a laboratory solar chimney with an energy storage system experimentally and numerically. A phase change material named as paraffin wax was selected as a heat storage. The relations between the output and input data were found by employing the multilayer neural network using MATLAB software. A small scale SCPP coupled with energy storage systems including soil, water and paraffin was investigated numerically by Bashirnezhad et al. [24]. The results showed that the electric energy production of SCPP with water and paraffin as energy storage material increased 6.2% and 22%, respectively in comparison with that without thermal storage. Yaswanthkumar and Chandramohan [25] numerically investigated two different models of small solar updraft tower which were named as case I and case II. Case I is considered without thermal storage and case II is defined with energy storage. They found that the temperature, velocity, and pressure of air is lower in case II in comparison with those in case I. Amudam and Chandramohan [26] investigated the variations of the performance parameters of a SCPP such as output power, efficiency of collector and overall efficiency of SCPP. The results were obtained from investigation of a solar chimney without thermal storage and with sand-rock mixture as an energy storage. They found that the performance parameters of a case with energy storage were lower than those of a case without thermal storage. Coupling of energy storage and solar chimney caused to the reduction in the maximum output power from 79.92 W to 63.8 W. In this article, the performance of a SCPP coupled with energy storage is numerically investigated where the energy storage is defined as soil with various porosities. The output power, heat and exergy loss from the outlet, and efficiency of SCPP are investigated under the effects of soil porosity, pressure drop of turbine and solar radiation. The wasted ability to produce power is evaluated through the investigation of exergy loss from the outlet of chimney. The valuable results of exergy loss can be used to proposed a hybrid system to take advantage of the lost energy and exergy. In the literature very little attention was paid to the investigation of the effects of the porosity of soil as energy storage layer on the operation of a SCPP. A comprehensive study about the effect of the soil porosity on the -3-

Journal Pre-proof results is made in this paper for the specific SCPP with the turbine which is modeled as pressure drop condition. The results of this study can be employed for choosing an appropriate location with suitable soil porosity and radiation flux for construction of SCPP to reach the highest efficiency and output power. 2. Definition of the problem Fig. 1 shows a schematic of SCPP identical to the Spanish prototype [4]. The SCPP consists of a chimney, collector and energy storage layer. The chimney is a circular cylinder with the height and the radius of 200 m and 5 m, respectively. The radius of the collector is defined as 122 m and the height of the collector from the ground is changed from 2 m in the inlet to 6 m in the center. The chimney and collector are connected smoothly to each other. The thickness of energy storage layer is set as 5 m. The applied materials for the energy storage and the canopy are soil and transparent glass, respectively. The density, the specific heat capacity and the thermal conductivity of the soil are defined as ρ = 1700 kg/m3, Cp = 2016 J/kg.K and λ = 0.78 W/m.K, respectively. The soil is modeled as porous media with various porosities such as 0.1, 0.2, 0.3 and 0.4. The flow of air in the energy storage layer is calculated using Brinkman–Forchheimer-extended Darcy model. The inlet of the collector and the outlet of the chimney are set as atmospheric pressure. Wall of the chimney is adiabatic with no-slip condition. The heat may be transferred from canopy by considering convection boundary condition. The convection coefficient and the environment temperature are set as 10 W/m2K and 293 K, respectively. The temperature at the lowest altitude of the energy storage layer is considered to be constant with the value of 300 K. The solar radiation is set as 200 W/m2, 400 W/m2, 600 W/m2 and 800 W/m2 which is defined as a heat source for the ground thin layer on the top of the energy storage [27]. Turbine of a SCPP, as explained in the literature [28], belongs to a pressure based wind turbine. The pressure drop is considered across the turbine by applying fan model. By passing through the turbine, the pressure of air significantly changes and the velocity of air does not alter. The solar chimney output power is obtained from the following equation [28]. (1) W   .PV . t

t

Where, ∆P denotes the difference in fluid pressure by passing through the turbine. ηt is the efficiency of the turbine which is defined as 80% in this study according to the literature [28, 29].

Figure 1 Solar chimney geometry and the boundary conditions -4-

Journal Pre-proof 3. Mathematical formulation and numerical procedure The governing equations of steady turbulent buoyant flow and heat transfer of air in the SCPP need to be solved simultaneously. The variation of air density is modeled by applying Boussinesq’s approximation. The energy storage is defined as porous media with various porosities and the soil is adopted as material of energy storage layer. Brinkman–Forchheimer-extended Darcy model and Navier–Stokes equation are employed to investigate the flow of air in the energy storage and the chimney regions, respectively. The equations for conservation of mass, momentum and energy with k – ε equations are written as follows where the subscripts 1 and 2 designate the parameters in the clear region (chimney) and the porous region (energy storage layer), respectively. (2)  u1  v1

x



   u1u1  x    u1v1  x

 

   Cu1T  x

   kui  xi    ui  xi

0

y



   v1u1  y    v1v1  y 



  2u  2u  P1    21  21  x y   x

(3)



  2v  2v  P1   g  T  T     21  21  y y   x

(4)

  2T  2T   1  2  2  y   x

(5)

   Cv1T  y

t       x j   k

  x j

      t  

(6)

 k     Gk  Gb    Sk  xi      x j

(7)

 2   C1  Gk  C3 Gb   C2   S k 

 u2  v2  0 x y

(8)

P2    2u2  2u2     CF 1     u2u2     v2u2         2    u2  u2   2 2    x y x   x y   K K  

(9)

P2 1     u2 v2     v2 v2      2 v2  2 v2      g  T  T         2  x y y   x 2 y 2     Cu2T  x



   Cv2T  y

    CF  v2  v2   K K   

(10) (11)

  2T  2T   2  2  2  y   x

where, λ2 is the effective thermal conductivity which is defined as follow.

2  (1   )s  1

(12)

As stated, the wasted ability to produce power from SCPP is studied in this article through the investigation of exergy loss from the outlet of chimney. The lost exergy due to the outlet mass flow rate of hot air from chimney into the atmosphere is defined from the following equation [30]. (13) Ex  ma   h  h0   T0  s  s0   The energy efficiency of solar chimney power plant is investigated as an important output parameter of SCPP from the following equation [31]. -5-

Journal Pre-proof Wt (14) E The partial differential equations are discretized by applying second order upwind scheme. The air is assumed to be incompressible and the pressure based solver is adopted. The standard scheme is chosen from available pressure interpolation schemes. The SIMPLE algorithm is selected as pressurevelocity coupling to derive a condition for pressure from the equation of continuity. The fluid flow is modeled near the walls by applying standard wall function. The structured grids are defined at the computational domain as shown in fig. 2. The grids are located closer to each other in the areas in the vicinity of the wall, the interface of porous and clear regions and the curved connection between the chimney and the collector. The independency of the results to the computational cells number is analyzed by increasing the number of the grids. It is found that grid-independent simulation results are obtained where the computational cells number is 546372.



Figure 2 Grid distribution in domain 4. Results and discussion The numerical model should be validated prior to presenting the results. Fig. 3 shows the comparison between the air temperature of the current numerical simulation and that of Spanish prototype [4]. The experimental air temperature was collected on 2nd September, 1982. The numerical results are obtained with the same boundary conditions that the experimental data was measured. Fig. 3 reveals that the numerical results of air temperature are in acceptable agreement with the experiments.

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Figure 3 Comparison between the current numerical result and available experiments [4] Moreover, the current numerical simulation is performed with the same boundary condition that the other experiments were measured [4]. The solar radiation is considered to be 1000 W/m2. The pressure drop of turbine is set as 0 pa similar to the no-load condition in the experimental investigation. The upwind velocity of air in the chimney and the temperature increase through the collector are reported in the following table. Table 1 The current results of air velocity in the chimney and the temperature increase through the collector and those measured by Haaf [4]. Results Temperature increase in the Air velocity at the base of collector (K) chimney (m/s) Experiments [4] 20 15 Current results 23.17 16.38 Table 1 shows that the percentage error of the current air velocity and temperature increase with respect to the experiments are %9.2 and %15, respectively. The difference between the results of the current study and those presented by Haaf [4] is due to the modeling of the thermal radiation by heat source in the numerical simulation. After examining of the accuracy of numerical simulation, the effects of various parameters on the flow and heat transfer characteristics of air in the solar chimney are investigated. Fig. 4 shows the effects of turbine pressure drop on the outlet temperature of the SCPP for various values of solar radiation. It is shown that the variation of air temperature at the outlet of the chimney can be investigated for the wider range of the turbine pressure drop with respect to those presented in the literature [28]. It is found that the temperature of air at the outlet of the chimney is ascending function of the turbine pressure drop and the solar radiation. By increasing of the pressure ratio, the variation of the chimney outlet temperature with respect to the solar radiation decreases and the variation of the air temperature at the outlet of the chimney with respect to the turbine pressure ratio increases.

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Figure 4 Chimney outlet temperature versus turbine pressure drop for various solar radiations The temperature in the domain for different radiations and pressure ratios of turbine are shown in fig. 5. By increasing of the solar radiation, it is expected that the temperature of air in all areas of collector, energy storage and chimney increases due to the absorption of the solar energy. The temperature of fluid in the all areas of the domain significantly increases as a result of the increase in the turbine pressure drop.

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Journal Pre-proof Figure 5 Contours of temperature (K) for various solar radiations and turbine pressure drops Fig. 6 shows the effects of radiation and pressure ratio of turbine on the pressure. As stated before, the turbine in a SCPP belongs to the pressure based impulse turbine. It means that the velocity of air does not change by passing through the turbine, but the pressure is altered under the effect of turbine. For this purpose, the fan boundary condition is adopted for definition of the turbine in the computational domain. Fig. 6 shows that the variation of pressure is significant in the region where the turbine is defined which can be expected from the fan model definition of the turbine. According to fig. 6, it can be found that the pressure of air decreases in the domain with the increase in solar radiation.

Figure 6 Contours of pressure (pa) for various solar radiations and turbine pressure drops Fig. 7 shows the effects of radiation and pressure drop of turbine on the velocity. It is demonstrated that the velocity of air in the solar chimney is an increasing function of radiation and a decreasing function of turbine pressure ratio. As explained before, the velocity of air does not change by passing through the region where the turbine is located.

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Figure 7 Contours of velocity (m/s) for various solar radiations and turbine pressure drops Fig. 8 shows the output power of SCPP under the effects of radiation and turbine pressure ratio. It is found that the output power of the SCPP is an ascending function of solar radiation. It means that in the area of the Earth with the high radiation, the use of the SCPP is more affordable. According to fig. 8, there is an optimum value of turbine pressure ratio for each solar radiation where the output power of the SCPP becomes maximum. It means that for the specific solar radiation, the suitable turbine should be selected to achieve the maximum output power. By increasing of the solar radiation, the peaks of the output power curves versus the turbine pressure ratio occur in the higher values of the turbine pressure drop.

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Figure 8 Output power of SCPP versus turbine pressure drop for various solar radiations Fig. 9 shows that the heat loss from solar chimney outlet increases with the increase in solar radiation, and it changes from the ascending function of turbine pressure drop to the descending function of turbine pressure drop by passing through the specific value of turbine pressure ratio for each solar radiation. By increasing of the solar radiation, the peaks of the heat loss from solar chimney outlet curves versus the turbine pressure ratio occur in the higher values of the turbine pressure drop.

Figure 9 Heat loss from solar chimney outlet versus turbine pressure drop for various solar radiations The variation of heat loss from canopy with respect to the turbine pressure drop for different solar radiations is shown in fig. 10. The heat loss from canopy is an ascending function of solar radiation and turbine pressure ratio. Comparison between fig. 9 and fig. 10 reveals that the heat loss from the canopy and the outlet of chimney increase with the increase in solar radiation. While, the variation of the heat loss from the canopy with respect to the turbine pressure ratio is different with the variation of that from the solar chimney outlet with respect to the pressure drop of turbine.

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Figure 10 Heat loss from canopy versus turbine pressure drop for various solar radiation Fig. 11 shows that the exergy loss from solar chimney outlet is an increasing function of solar radiation and decreasing function of turbine pressure drop. Contrary to the variation of the heat loss from the solar chimney outlet with respect to the turbine pressure ratio, there is not any peaks in the curves of exergy loss from the outlet of solar chimney versus the turbine pressure ratio. It means that the wasted ability to produce power from solar chimney outlet increases with the increase in solar radiation and decrease in turbine pressure drop.

Figure 11 Exergy loss from solar chimney outlet versus turbine pressure drop for various solar radiations The energy storage layer in this article is defined as soil. The SCPP can be constructed on the soil with different porosities. The effects of the soil porosity on the performance of SCPP is studied in this investigation. Fig. 12 shows that the output power of SCPP in all cases with different thermal radiation decreases with the increase in the porosity of soil on which the solar chimney is constructed. Also, it can be found that the effects of soil porosity on the output power of the SCPP is more significant at higher values of turbine pressure drop. At lower turbine pressure ratio, there is no appreciable difference between the curves of output power versus the turbine pressure drop for various soil porosities. The temperature of air becomes higher with the increase in solar radiation - 12 -

Journal Pre-proof which leads to the decrease of the air density. Consequently, the air flows more strongly upward and the output power of turbine increases.

Figure 12 Effects of energy storage layer porosity and pressure drop of turbine on the output power of SCPP at the solar radiation of (a) 200 W/m2, (b) 400 W/m2, (c) 600 W/m2 and (d) 800 W/m2 Fig. 13 shows the effects of turbine pressure ratio and soil porosity on the heat loss from the canopy at different values of thermal radiation. The heat loss is an increasing function of turbine pressure drop. The variation of heat loss with respect to the soil porosity is much lower than its variation with respect to the pressure ratio of turbine. It is found that the heat loss from canopy is descending function of soil porosity at lower values of turbine pressure drop and it is ascending function of soil porosity at higher values of turbine pressure ratio. For all values of soil porosity and turbine pressure drop, the heat loss from canopy increases by increasing of the thermal radiation.

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Figure 13 Effects of energy storage layer porosity and pressure drop of turbine on the heat loss from canopy at the solar radiation of (a) 200 W/m2, (b) 400 W/m2, (c) 600 W/m2 and (d) 800 W/m2 Fig. 14 shows the variation of heat loss from solar chimney outlet with respect to the turbine pressure ratio and soil porosity at various values of thermal radiation. It is found that the heat loss from outlet becomes maximum at specific value of turbine pressure drop for each solar radiation and soil porosity. The heat loss from chimney outlet is increasing function of thermal radiation and decreasing function of soil porosity. The behavior of heat loss under the effects of soil porosities and turbine pressure ratio changes by increasing of the radiation from 200 W/m2 to 400 W/m2. It is found that the variation of heat loss from solar chimney outlet with respect to the soil porosity is more significant in the higher values of turbine pressure ratio at the thermal radiation of 200 W/m2; whereas, that is more significant in the lower values of turbine pressure drop at the thermal radiation of 400 W/m2, 600 W/m2, and 800 W/m2.

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Figure 14 Effects of energy storage layer porosity and pressure drop of turbine on the heat loss from solar chimney outlet at the solar radiation of (a) 200 W/m2, (b) 400 W/m2, (c) 600 W/m2 and (d) 800 W/m2 Fig. 15 shows the effects of the soil porosity, turbine pressure ratio and solar radiation on the exergy loss from solar chimney outlet. The exergy loss from the outlet of the chimney increases where the temperature of the outlet air becomes higher due to the increasing of the thermal radiation. The exergy loss from the outlet decreases with the increase in turbine pressure ratio and soil porosity. At the thermal radiation of 200W/m2, the variation of exergy loss from solar chimney outlet with respect to the soil porosity is more significant at the higher values of turbine pressure ratio; whereas, at thermal radiation of 400W/m2, 600W/m2, and 800W/m2, it is more important at lower values of turbine pressure drop.

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Figure 15 Effects of energy storage layer porosity and pressure drop of turbine on the exergy loss from solar chimney outlet at the solar radiation of (a) 200 W/m2, (b) 400 W/m2, (c) 600 W/m2 and (d) 800 W/m2 Fig. 16 shows the effects of thermal radiation, soil porosity and turbine pressure drop on the efficiency of the SCPP. The results indicate that the efficiency of the SCPP is higher in the places where the radiation flux is lower. But it should be noted that at low radiation flux, the output power of the SCPP is not appreciable and therefore the construction of solar chimney is not suitable in terms of power generation. Quantitative examination of efficiency and power generation reveals that by increasing in the values of thermal radiation from 200W/m2 to 400W/m2, 400W/m2 to 600W/m2, and 600W/m2 to 800W/m2, the efficiency of SCPP decreases %5.59, %1.63 and %0.68, respectively and the output power of SCPP increases %88.82, %47.56 and %32.42, respectively. The results show that by increasing of the radiation flux, the reduction in efficiency compared to the increase in output power is negligible. Hence, the location with the highest radiation is chosen as the most suitable place for construction of solar chimney.

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Figure 16 Effects of energy storage layer porosity, solar radiation and pressure drop of turbine on the efficiency of the solar chimney power plant The investigation of the effects of soil porosity on SCPP efficiency shows that the efficiency of the system is lower in places with higher soil porosity. Simultaneous examination of the energy efficiency and output power reveals that with increasing in soil porosity, not only energy efficiency decreases but also power output decreases. Therefore, the land with less porosity is more suitable for construction of SCPP in terms of energy efficiency and output power. 5. conclusion The performance of SCPP with soil energy storage layer is investigated under the effects of solar radiation, turbine pressure drop and porosity of soil on which the solar chimney is constructed. The numerical simulation is performed to investigate the flow and heat transfer characteristics of air in the chimney and storage layer. The results indicate that the outlet air temperature from the chimney increases with solar radiation and turbine pressure drop. The pressure in domain decreases with solar radiation, and the variation of pressure in the flow field is significant in the region near the turbine. The velocity in domain increases with solar radiation and it decreases with the increase in the turbine pressure ratio. The heat loss from solar chimney outlet and canopy increases in a place with higher radiation. The heat loss from the outlet of solar chimney becomes maximum at the specific value of turbine pressure drop; whereas, the heat loss from canopy is an increasing function of turbine pressure ratio. The variation of heat loss from canopy due to the change in the soil porosity is negligible and the heat loss from solar chimney outlet decreases with the increase in the porosity of energy storage layer. Moreover, it is found that exergy loss from solar chimney outlet is an increasing function of solar radiation and decreasing function of turbine pressure drop and soil porosity. For each solar radiation and soil porosity, the output power and efficiency of SCPP becomes maximum at specific value of turbine pressure drop. The efficiency of the SCPP is higher in the places where the radiation flux is lower; whereas, the output power of the SCPP is not appreciable at low radiation fluxes. Quantitative examination of efficiency and power generation reveals that by increasing in the values of thermal radiation from 200W/m2 to 800W/m2 the maximum reduction in the efficiency of SCPP and maximum increase in the output power of turbine are obtained %7.76 and - 17 -

Journal Pre-proof %268.96, respectively. It is shown that the reduction in efficiency compared to the increase in output power is negligible by increasing of the radiation flux. Hence, the construction of solar chimney in a place with the high radiation is most appropriate. It is found that the efficiency and output power of SCPP is higher in the places with the lower soil porosity. The result shows that the efficiency of system and output power of turbine increase %3.04 by reduction in the porosity of soil from 0.4 to 0.1. It can be concluded that the soil with less porosity is more appropriate for construction of SCPP to achieve higher energy efficiency and output power. 6. References 1. Sedighi, A.A. and M. Bazargan, A CFD analysis of the pollutant dispersion from cooling towers with various configurations in the lower region of atmospheric boundary layer. Science of The Total Environment, 2019. 696: p. 133939. 2. Sedighi, A.A., Z. Deldoost, and B. Mahjoob Karambasti, Flow and Heat Transfer of Nanofluid in a Channel Partially Filled with Porous Media Considering Turbulence Effect in Pores. Canadian Journal of Physics, 2019(ja). 3. Haaf, W., et al., Solar chimneys part I: principle and construction of the pilot plant in Manzanares. International Journal of Solar Energy, 1983. 2(1): p. 3-20. 4. Haaf, W., Solar chimneys: part ii: preliminary test results from the Manzanares pilot plant. International Journal of Sustainable Energy, 1984. 2(2): p. 141-161. 5. Kasaeian, A., E. Heidari, and S.N. Vatan, Experimental investigation of climatic effects on the efficiency of a solar chimney pilot power plant. Renewable and Sustainable energy reviews, 2011. 15(9): p. 5202-5206. 6. Gholamalizadeh, E. and S. Mansouri, A comprehensive approach to design and improve a solar chimney power plant: A special case–Kerman project. Applied Energy, 2013. 102: p. 975-982. 7. Kasaeian, A., et al., 3D simulation of solar chimney power plant considering turbine blades. Energy Conversion and Management, 2017. 147: p. 55-65. 8. Toghraie, D., et al., Effects of geometric parameters on the performance of solar chimney power plants. Energy, 2018. 162: p. 1052-1061. 9. Hassan, A., M. Ali, and A. Waqas, Numerical investigation on performance of solar chimney power plant by varying collector slope and chimney diverging angle. Energy, 2018. 142: p. 411-425. 10. Ayadi, A., et al., Experimental and numerical analysis of the collector roof height effect on the solar chimney performance. Renewable energy, 2018. 115: p. 649-662. 11. Jafarifar, N., M.M. Behzadi, and M. Yaghini, The effect of strong ambient winds on the efficiency of solar updraft power towers: A numerical case study for Orkney. Renewable energy, 2019. 136: p. 937-944. 12. Gholamalizadeh, E. and M.-H. Kim, Thermo-economic triple-objective optimization of a solar chimney power plant using genetic algorithms. Energy, 2014. 70: p. 204-211. 13. Gholamalizadeh, E. and M.-H. Kim, Multi-objective optimization of a solar chimney power plant with inclined collector roof using genetic algorithm. Energies, 2016. 9(11): p. 971. 14. Najm, O.A. and S. Shaaban, Numerical investigation and optimization of the solar chimney collector performance and power density. Energy conversion and management, 2018. 168: p. 150-161. 15. Sheikholeslami, M., Z. Li, and A. Shafee, Lorentz forces effect on NEPCM heat transfer during solidification in a porous energy storage system. International Journal of Heat and Mass Transfer, 2018. 127: p. 665-674.

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Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

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Performance of solar chimney power plant (SCPP) with soil energy storage layer is investigated numerically. Output power becomes maximum for each solar radiation and soil porosity at the specific value of the turbine pressure ratio. Construction of SCPP in a place with the high radiation is most appropriate in terms of energy efficiency and output power. Less porosity of soil on which the SCPP is constructed leads to achieve high efficiency and output power.