kourosh javaherdeh

Spray dryers account for about 45% of the gas consumption of a ceramic factory. Therefore, optimizing the energy consumption of this equipment is very important for the owners of the ceramic production industry. In this paper, two heat exchangers along with 30% recirculation of exhaust air are used to recover the exhaust heat from the spray dryers and use them to preheat the atomizing and drying air. The H-type finned heat exchangers with circular holes are used here and all results are extracted by two different approaches, including standard k-ε and SST k-ω models. First, the influence of different parameters on the performance of the first and second heat exchangers evaluated. It is shown that the Nusselt number increases by increasing the Reynolds number, While the friction factor of both heat exchangers decreases. Then, the influence of adding heat exchangers on the energy consumption of the factory and spray dryer estimated. It is shown that the suggested system can be effectively used to 12.04% decrease the energy consumption of the spray dryer.

 By improving the performance of the heat exchanger, it is possible to reduce the size and production costs of the heat transfer, and this leads to a reduction in fuel consumption and better environmental protection. To this purpose, engineers have proposed several ways to increase the heat transfer. The heat transfer rate of a turbulent non-Newtonian fluid flow in a heat exchanger with partially porous media is numerically investigated in this paper. The effects of power-law index of the fluid and Darcy number on the heat transfer rate and thermal performance of turbulent flow are studied and compared to each other.

 The research model is simulated in the FLUENT computational fluid dynamics software using Finite Volume Method and the flow and energy equations are discretized up to the second order upwind.

The pseudo-plastic fluid has the highest heat transfer rate and thermal performance compared to Newtonian and dilatant fluids. According to the findings, the heat transfer rate and thermal performance increase with decreasing Darcy number. Investigation of the effect of non-dimensional porous layer area (S) on the Nusselt number and thermal efficiency in different Darcy numbers shows that, the Nusselt number has the highest value in S=0.9 and thermal efficiency has the highest value in S=0.76.

 S=0.76 is the optimal porous layer thickness. Therefore, porous layer with S=0.76,  and the pseudo-plastic fluid are recommended for the optimal thermal efficiency.

In this research, two different structures of the combined system of supercritical Brayton cycle of carbon dioxide with regenerator along with organic Rankine cycle and also the combined system of supercritical Brayton cycle recondensation with organic Rankine cycle with heliostat collector from the point of view of energy and economic-exergy simulated and compared. R123 fluid has been used in organic cycle due to its suitable thermophysical and environmental properties. The results indicate that with the change of the influencing parameters such as the compressor pressure ratio and the turbine inlet temperature, the work output of the system with the regenerator has been higher in all the examined efficiencies, but the exergy efficiency of the recompression system is higher in the ratio of low pressures in the compressor. Also, despite the higher overall cost rate of the system with the regenerator, this system creates a lower electricity production cost. Other simulation results indicate that the highest amount of exergy destruction occurs in the solar collector that is about 9726 kW. And the solar collector, having the highest cost rate, should be examined more than other components from an exergy-economic point of view. Finally, a parametric analysis has been done the effects of the change in compressor pressure ratio with 3485$/h, turbine inlet temperature, and low pressure, on the performance of the system, from the perspective of energy and exergy-economics.

This article investigates the effect of using three nanofluids as exhaust gas cooling fluid in an EGR cooler. Reducing the exhaust temperature of diesel engines can reduce environmental and thermal pollutants. In a conventional 3-liter engine in all kinds of vehicles, 20 to 40 kW of its 115 kW power is being wasted. The engine shell temperature rises to 600 degrees Celsius.  Exhaust gas recirculation can recover a part of it. Exhaust gas recirculation can recover thermal energy by exhaust gas recirculation method by charging a thermal energy storage tank to feed a diesel engine in cold start.Many researchers have simulated natural convection in the nanofluids. The innovation of the current research is the use of 61 tubes inside the small heat exchanger that is cooled by the discussed nanofluids in the exhaust gas recirculation system of the diesel engine that works with the paraffin phase changer and the exhaust gas recirculation rate is 60% to Reduce of environmental pollution and smoother operation of diesel engine. The inlet is steady state turbulent. The thickness of the inner tubes is considered close to zero. The shell is adiabatic. Both of them exit the heat exchanger under pressure. Three nanoparticles of diamond, silicon dioxide, and copper are considered. This numerical simulation has solved the continuity equations, energy, Navier-Stokes, the pressure drop along the pipe, flow, and rotation equation, kinetic energy disturbance, and energy loss rate equation. The results showed a higher pressure drop for the silicon dioxide-ethylene glycol nanofluid. Silicon dioxide-ethylene glycol nanofluid has a higher Nusselt number, slightly different from other nanofluids. Also, Copper ethylene glycol has a lower Velocity among nanofluids

In this study, investigated heat transfer of Nanofluid laminar flow in a channel with obstacles along different geometry such as triangular, rectangular and half-cylinder and the effect of adding Nano particles on based flow. The result showed that the average Nusselt number increased with an increasing volumetric fraction of nano particles. However, the increasing average Nusselt number is dependent on the type of obstacles geometry that rectangular shape is more than others, because area of heat transfer is more than other obstacles. The Nusselt number with rectangular geometry is 30% more than the Nusselt number with half-cylinder geometry. Also, using obstacles with different geometry and the adding of the nanoparticles, the hydraulic-thermal performance has been increased up to 44%. The local Nusselt number for nanofluid of volume fraction with 1% is 2.38% higher than volume fraction of nanofluid with 2%. The local Nusselt number of volume fraction of nano particle with 1% is 10% less than based fluid.

In this paper, a multi-component multiphase pseudopotential Lattice Boltzmann method with multi relaxation time (MRT) collision operator is presented to examine the dynamic behavior of liquid droplets movement and coalescence process in the gas channel of PEMFC. In the numerical method, the forcing term is improved to achieve a high-density ratio and thermodynamic consistency. First, the density ratio, Laplace law, and contact angle are validated with previous studies. Then, different parameters, such as operating temperature, pressure difference, surface contact angle, the radius of droplets, and distance between two droplets on the droplet movement and coalescence process are studied. The results revealed by rising temperature from 30 to 80 degrees, the speed of drop increases around 6 percent. The simulation results indicated that the rising of pressure gradient increases the gas flow velocity on the channel and leads to increasing the shear force and eventually faster movement of the droplet on the gas channel. Also, investigation of various contact angles shows that a hydrophilic surface causes a resistance force between the droplet and the wall and delays the removal of droplets. Moreover, droplet coalescence is useful for droplet movement because of increasing the velocity gradient on top of the droplet; consequently, the shear force on the droplet is raised during coalescence.

In this research, the heat transfer behavior of a wavy mini-channel heat exchanger was studied. Using the experimental data of heat transfer, the convective heat transfer coefficients were estimated. Among numerous trials, the Nusselt number (Nu) best correlation is a linear function of Reynolds number (Re) independent of Prandtl number (Pr), and similar correlations for hot and cold sides were obtained. The coefficient range is 0.01 to 0.03 for different fluids. The previous experimental works verify this conclusion. Also, in the case of non-Newtonian fluids and nanofluids, the definition of Re is related to its rheological behavior. However, if the velocity profile is specified, it can be used to derive the relation between the Fanning friction factor (Cf) and Re. Here, a suitable velocity profile for wavy configuration is used, and the experimental values of Re are estimated by the experimental pressure drop data. It is shown that the application of the derived relation between Cf and Re is preferred compared to the assumption of a circular pipe that is convenient for fluid mechanics studies. In addition, it is proved that if experiments with different fluids or relative waviness are done at similar flow rates, the U versus the Re plot can be used to compare heat exchanger performance.

In the present study, heat transfer enhancement of a non-Newtonian nanofluid by different arrangements of double fins in a corrugated channel was numerically investigated. Finite volume method is used to solve governing equations of flow and energy with assumptions of 2D, steady-state, and single phase. The fluid flow is in the hydraulically laminar regime and the channel is under a constant heat flux. A set of case studies are conducted for a corrugated channel model to analyze the influence of the main contributing factors; Reynolds number, nanofluid volume fraction, the different fin configurations, on the flow field and the heat transfer characteristics as well. . Results indicate that using non-Newtonian fluid of water+0.5%CMC instead of water fluid leads to enhance heat transfer. The numerical results showed that implementing configuration D in a corrugated channel leads to heat transfer rate compared to other configurations. Besides, for configuration D, raising the Reynolds number from 200 to 1000 and the nanofluid volume fraction from 0.5% to 1.5% cause the mean Nusselt number and performance evaluation index to increase about 9.85% and 9.09%, respectively.

Combined heat and power systems are used for renewable energies and reducing fossil fuels. This work, investigated energy efficiency, exergy, and exergy economic a Brayton cycle and refrigeration cycle with an ejector that used solar energy as a heat source. Inlet pressure turbine, outlet pressure turbine, inlet temperature turbine, and temperature of the evaporator are variable parameters, when one of the parameters changes, the other parameters are kept constant so that the thermodynamic analysis focuses on important parameters. Results showed that inlet pressure of initial flow in ejector and outlet velocity of flow on ejector are increased with increasing outlet pressure of turbine. The storage tank had the most exergy destruction rate among all components for the high-temperature difference that it’s almost 29% from all of the exergy destruction rates. Also, the highest cost per unit of power is related to the combined heat and power cycle that it’s about 53% of the total cost.

In this research, studied the coefficient of performance (COP) and second low of thermodynamic on Lithium bromide double effect refrigeration cycle using solar energy and gas fuel. Coefficient of performance, total and each component Exergy losses are calculated with various initial conditions on double effect refrigeration cycle using solar energy and gas fuel. It’s assumed that all of the each component are in isentropic condition, therefore, they are in optimized state. This study is based on Tehran which is at 35.2 degrees of latitude for calculating solar energy. Also, used a flat collector for receiving heat and energy of sun. The results showed that temperature of high and low pressure of generator are 150 C˚and 83 C˚ respectively. Also, the optimum pressure value of in solution pump is 90 KPa. The value of exergy losses is increased with increasing evaporator cooling load. The maximum of total exergy losses in solar-gas system is for absorber and after that belonged condenser, high pressure heat exchanger, low pressure heat exchanger and evaporator respectively. But, the maximum of total exergy losses in gas system is for high pressure heat exchanger and after that belonged absorber, condenser, high pressure hear exchanger and evaporator.

In this paper, the effect of opposite baffles on the flow field and the increase of forced heat transfer of non-Newtonian nanofluid flow in a laminar regime in a backward-facing step are investigated numerically. The finite volume method is used to solve the governing equations of flow and temperature. Besides, the impact of geometric parameters such as horizontal distance between baffles to the edge of the stairs and its numbers, like Reynolds number, nanoparticle volume fraction, and the non-Newtonian fluid behavior on the flow field and heat transfer have been examined. Results demonstrate that using non-Newtonian fluid instead of Newtonian fluid enhances heat transfer and reattachment length. Raising the Reynolds number and the nanofluid volume fraction causes the mean Nusselt numbers and the Performance Evaluation Index to increase. The outcomes indicate that using a pair of opposite baffles must be more beneficial than the other number of baffles.

In this study, the numerical analysis was studied about mixed convection of sodium alginate (non Newtonian Pseudoplastic fluid) with Nano particle in a two dimensional rectangular channel containing several blocks. The temperature of inlet fluid to the rectangular channel were kept in steady state and fixed temperature that is less than wall temperature. To solve the Continuity, momentum and energy equations, numerical analysis and finite volume method with SIMPLE technique is used. In this study the effect of height and numbers of blocks, volume fraction of nano particle, Richardson number and Reynolds number is investigated on Nusselt number and skin friction coefficient. The results show that increasing of aluminum solid particles in sodium alginate will increase the heat transfer rate and skin friction coefficient in channel length. Also by increasing Reynolds number there is an increase in convection rate through the channel. In addition to the conclusions, increasing the block height from H/3 to H/2 enhance the average Nusselt number by 10% and skin friction coefficient by 13%. It is observed that increasing of Richardson number decreases the Nusselt number and skin friction coefficient. Also changing block number from 3 to 5 decrease Nusselt number about 3.5%.

In this research, the thermal and hydrodynamic behavior of a non-Newtonian nanofluid turbulent flow in the counterflow arrangement in a double pipe helical heat exchanger is numerically simulated. A solution of carboxymethyl cellulose powder in water with a mass percentage of 0.1% with a nanoparticle of aluminum oxide as a working fluid has been used. The CFD commercial software Fluent was used to solve the governing equations while the turbulent flow was simulated using k-ε turbulent model; the results were in a good agreement with experimental data. The effect of important parameters such as curvature, Reynolds number and volume percentage of aluminum oxide nanoparticles on the heat transfer has been investigated. The results show that as the curvature ratio increases in constant Dean (Dn) numbers, the Nu number and the coefficient of friction increases. The addition of nanoparticles of aluminum oxide to the base fluid for the flow with the constant Reynolds and Dn number increases the heat transfer and increases the pressure drop in the helically coiled tubes. The centrifugal force generated by the curvature of the coiled tube results in a secondary flow in the heat exchanger so that the heat transfer and pressure drop increased up to 35% and 30%, respectively, compared to the straight tubes. The effect of heat transfer enhancement methods on the hydrodynamic index has also been studied, so that in the helical coils, the amount of hydrodynamic index increased with decreasing curvature ratio and increasing the volume concentration of nanoparticles.

Heart failure claims the lives of thousands of people annually. Left ventricular assist device is a valid treatment option for patients with an advanced stage of heart failure. The left ventricular assist device is a blood pump increasing the pumping ability of the bottom left chamber of the patient's heart. In this study, we investigate the hemolytic characteristics of a left ventricular assist device. The main objective of this paper is to explore the effects of amplitude and frequency on levels of hemolysis via computational fluid dynamic in an implantable reciprocating pump. Thus, the dynamic mesh technique is utilized to simulate piston motion and valves closure. Moreover, a system of time-dependent nonlinear partial differential equations is coupled with each other to predict blood flow and hemolysis index. Fluid dynamic characteristics are obtained by employing continuity and momentum equations and the levels of hemolysis are also calculated by applying two additional scalar transport equations based on an Eulerian transport approach. The results depicted the favorable reduction in hemolysis index by increasing frequency and decreasing amplitude simultaneously at specific Reynolds number, they also showed that the average hemolysis at the right side of the piston is slightly higher than the left side and it obtains its maximum value at valves and clearance domains.

This study proposes and evaluates a new cogeneration system for zero-energy buildings. Zero-energy buildings are those in which the net electrical energy exchange between power grid and building equals zero. The proposed system is comprised of a biomass gasifier, an internal combustion engine, a double-effect lithium bromide-water absorption chiller, a backup boiler for hot water production, a gas storage tank, a hot water storage tank, and two heat exchangers. The system is supposed to provide the building with the electricity, hot water, heating and cooling requirements over the year. Besides presenting a functional strategy for the proposed system, this study evaluates the sensitivity of the objectives of the system (i.e., fulfilling the electricity, hot water, and heating and cooling requirements) to some main decision variables, including the capacity of engine, chiller and boiler, the volume of hot water tank, the start-up time of the internal combustion engine. The results indicate that the proposed system is able to support a zero energy building. The results also demonstrate that an increase in the input power of the engine helps to achieve the goal of zero-energy buildings. Moreover, it is observed that the system is most economical when the cooling capacity of the absorption chiller approaches the heating and cooling demands of the building. The results also indicate that the start-up time of the combustion engine would be more influential in the case of high electricity demand conditions.

This study focuses mainly on employing trombe wall systems to provide the heat required for restoring the desiccant wheel and investigating the optimal surface area of the wall for attaining air conditioning comfort. In this study, a solar desiccant wheel was modeled that receives the thermal energy required for regeneration from a trombe wall. In this system, first, the components of the desiccant wheel, the trombe wall, and the insolation were separately modeled in MATLAB and then assembled. The integrated system may be examined in all humid weather conditions around the globe. The results of the model are compared with the experimental results and have acceptable agreement with each other. The model had been developed for cooling the building in July in Rasht city by using the ground heat exchanger. A ground coil was incorporated in this system to pre-cool the process air. The optimal surface area of the trombe wall was extracted as a function of the parameters of the desiccant wheel. For a wall output temperature of 66 °C, the comfort temperature was found to be 24 °C, the humidity ratio to be 12 gw/kgra, and the optimal wall surface area to be around 52 m2.

In present paper is to study numerical simulation by using Finite volume method for Newtonian and non-Newtonian fluid flow inside corrugated tube equipped with typical twisted tape (TT) and V-cut twisted tape (VTT) at constant heat flux. For validation of this simulation, this results compared with empirical correlations of researchers. In this analysis water was as Newtonian fluid and 0.2 wt % carboxymethyle cellulse (CMC) in water was as a non-Newtonian fluid, the range of Reynolds number for Newtonian and non-Newtonian fluid varied (5300 to 25700) and (2400 to 6800) respectively. In this analysis, the effects of using different turbulence models, variable heat flux and creating V-cut on Nusselt number and friction factor is investigated. The obtained results showed that standard κ -ω model of turbulence for Newtonian fluid is a proper model rather than the other models and it had good agreements between experimental data, and the average differences for Nusselt number in typical and V-cut twisted tapes were less than 15.2% and 14.4% respectively. On other hand, in identical condition for non-Newtonian fluid, using of standard κ - ε model of turbulence is a proper model and the average differences on Nusselt number for typical twisted tape were less than 18%.

This study focuses mainly on employing trombe wall systems to provide the heat required for restoring the desiccant wheel and investigating the optimal surface area of the wall for attaining air conditioning comfort. In this study, a solar desiccant wheel was modeled that receives the thermal energy required for regeneration from a trombe wall. In this system, first, the components of the desiccant wheel, the trombe wall, and the insolation were separately modeled in MATLAB and then assembled. The integrated system may be examined in all humid weather conditions around the globe. The results of the model are compared with the experimental results and have acceptable agreement with each other. The model had been developed for cooling the building in July in Rasht city by using the ground heat exchanger. A ground coil was incorporated in this system to pre-cool the process air. The optimal surface area of the trombe wall was extracted as a function of the parameters of the desiccant wheel. For a wall output temperature of 66 °C, the comfort temperature was found to be 24 °C, the humidity ratio to be 12 gw/kgra, and the optimal wall surface area to be around 52 m2.

Organic Rankine Cycles are appropriate technology for the conversion of low quality thermal energy to electrical power. In this research the organic Rankine cycle was studied from energy, exergy and exergo-economic points of view, and it was simulated with hybrid solar and geothermal heat source in order to produce electricity and hot water. In this configuration, 90℃ geothermal brine was used to preheat the organic fluid and 150℃ solar fliud was used for organic fluid evaporation. Waste heat in condenser was also used to produce hot water. Simulation results show that power energy and exergy efficiency of combined heating are 0.566 and 0.156 and electrical energy and exergy efficiency are 0.057 and 0.065, respectively. Moreover, the amount of work output and total irreversibility are 50 and 671.1, respectively. Solar collector, the evaporator and condenser are the most important components from the exergo-economic point of view, due to the high initial cost rate and Exergy destruction. Parametric analysis result shows that the temperature increase in evaporator has positive effect on cycle operation and causes the increase in electricity efficiency and decrease in irreversibility. Also, the increase in pinch point temperature difference of evaporator has a negative effect on cycle operation. From economic point of view, the increase in evaporator and pinch point temperature difference of evaporator causes the decrease in capital coast rate. Also, the solar radiation change find to have positive effect on system operation, based on exergo-economic point of view, which causes the increase in energy and exergy efficiency.

In this study, turbulent mixed convection heat transfer and pressure drop of Al2O3/water nanofluid in helically coiled tube heat exchangers were investigated. Thermo-physical properties of nanofluid and base fluid were considered temperature dependent and analysis for helical coils, with curvature ratios of 0.1, 0.0666 and 0.05, and nanoparticles with volume concentrations in the range of 0-2% in various Reynolds number were carried out. CFD analysis was done by 3D realizable ke turbulent model in ANSYS FLUENT 15. According to the results, it was shown that by increasing the coil curvature ratio and nanoparticles volume concentrations in a same Reynolds number, heat transfer coefficient and pressure drop of helical coils both increased. Using numerical data, a correlation for predicting outer Nusselt number in terms of Rayleigh number in helical coils were proposed. Thermal performance index were compared in various conditions and the maximum value was noticed for coil with a curvature ratio of 0.1 and nanoparticles volume concentrations of 2%. Results showed that using nanofluid and helical coils instead of base fluid and straight pipes, improves thermal performance of the heat exchangers.

Considering the daily increase of consumption and expense of nonrenewable energies such as natural gas and electricity, application of clean and renewable energies such as solar thermal energy nowadays has been highly taken into consideration. In this research, at first, simple steam Rankine cycle and two different configurations of combined steam and organic Rankine cycles with parabolic trough solar collector as heat source are simulated from energetic and exergetic point of view. First configuration was basic steam rankine cycle with parabolic trough solar collector (PTSC) as heat source, and other configurations of the combined cycle worked as follows: In the second configuration (combined cycle with intermediate heat exchanger), with the increase of steam condenser pressure, heat dissipation in condenser is used as heat source for bottoming organic Rankine cycle and in the third configuration (combined cycle without intermediate heat exchanger), reduced-temperature solar fluid moving output of steam rankine cycle acted as the organic Rankine cycle heat source. Simulation results in the basic input state show that third configuration has the maximum amount of work and irreversibility and second configuration has the minimum amount of work and irreversibility which in this case, increase in the steam cycle condenser pressure leads to the reduction of work of combined cycle with intermediate heat exchanger, even lower than the simple steam cycle. On the other hand, second configuration has the maximum solar energy and exergy efficiency among three configurations which is due to the reduction of collector area required in this configuration.

In this research, ammonia-water regenerative Rankine cycle driven by solar energy and LNG as it’s heat sink in condenser, is simulated from the energy, exergy and exergoeconomic point of view. A relatively new method is used to implement pinch temperature difference in heat exchangers which causes improving of the thermodynamic performance and output power of the system. Also heat exchangers are simulated by using heat transfer correlations of shell and tube heat exchanger in details. The results of based condition showed the suitable performance of natural gas cycle from the thermodynamic and exergoeconomic point of view and notifies the importance of using the natural gas cycle. Solar collector and condenser of ammonia-water cycle because of their high cost value, are introducing as the components that shoud be more concidered from the exergoeconomic viewpoint. The parametric analysis results show that in high inlet pressure of ammonia-water turbine, the exergy efficiency and the total cost of the system heve more suitable values while the net output power of the system decreases. Also by changing the ammonia mass fraction, changing of output parameters has a complicated patern. Finally by increasing the pinch temperature difference in heat exchangers, the decreased amount of system’s thermodynamic performance is more than the amount of system’s economical performance improvement.

In this study, at first the combined steam and organic Rankine cycles, have been stimulated with high-temperature wasted hot gases recovery, from the energy and exergoeconomic points of view. In the configuration of the combined cycles, the high-temperature wasted gases acts as the source of steam cycle evaporator, then the decreased temperature exhaust gas of the steam cycle evaporator, is used as the low temperature source of organic cycle evaporator. Afterward the effects of changing different parameters such as temperature of the evaporator and condenser of steam cycle and pinch temperature difference, on the amount of total output work, total irreversibility, energy efficiency, exergy efficiency and exergoeconomic variables have been checked. The results in base state show that, energy and exergy efficiency of combined cycles are 0.2782 and 0.5279 respectively and the amount of output work and total irreversibility are 71401kW and 43616kW respectively. Total exergoeconomic factor for the combined cycles is 12.47 percent, which represents a high exergy destruction in components and recommends raising the initial cost of components in order to improve the performance of system. The evaporator, turbine and condenser of steam cycle, are the components that should be considered from the perspective of the exergoeconomic, because they contains the maximum amount of total initial costs and the cost of exergy destruction.

The performance of a cogeneration cycle with various working fluids is investigated and optimized with an economic approach. Exergy and exergoeconomic models are developed to investigate the thermodynamic performance of the cycle, and to assess the cost of products. In this study, the dynamic model would be registered to search the system behavior during a day. In this study, hydrogen production rate optimal design (HPROD) refrigeration power optimal design (RPOD) and cost optimal design (COD) are considered for analysis and optimization. According to recent parametric studies, boiler, turbine and condensation temperature and turbine inlet pressure affect the unit cost of products significantly. The results show the carbon dioxide and n-octane has a better operation to produce of hydrogen and refrigeration power among other working fluids, respectively. It is observed that, in carbon dioxide cycle, the SUCP is decreased by 8.5% when hydrogen production rate is decreased from 1.811 lit/s to 1.757 lit/s, therefore, in n-octane cycle, SUCP is decreased by 47.4% when refrigeration power is decreased from 9.599 KW to 6.622 KW. The evaluation of exergy destruction demonstrates in which the condenser has the highest exergy destruction, therefore, its rate in COD case is the lowest among the three other states. The results indicate, in carbon dioxide and n-octane cycles, the total exergy destruction and the investment cost rates in the RPOD case is higher than any other cases.