Heat Source Conditions Research Articles

MHD opposing flow of [formula omitted] hybrid nanofluid under an exponentially stretching/shrinking surface embedded in porous media with heat source and slip impacts

In the realm of fluid mechanics, the flow of a hybrid nanofluid under an exponentially stretching/shrinking surface has been extensively investigated by researchers due to its capability in altering the flow and heat transfer characteristics. Considering the above-mentioned setup with the addition of porous media, this study investigates the flow and heat transfer characteristics of Cu–TiO2/water hybrid nanofluid in the presence of magnetohydrodynamics, heat source, and slip conditions. The complex governing equations, originally in PDEs were transformed into ODEs using a similarity transformation, and the numerical result was obtained using the MATLAB bvp4c function. The Cu–Al2O3/water was found to be conducting scarcely higher rate of heat transfer compared to Cu–TiO2/water. The Cu–TiO2/water hybrid nanofluid boosted heat transfer by 4.04% when compared to water, whereas Cu/water nanofluid enhanced heat transfer by 2.13%. Dual solutions were found, and the stability analysis proved that the upper branch solution is stable. Moreover, the additional MHD and permeability parameter accelerates the skin friction, whereas copper nanoparticle volume fraction expands the heat transfer rate of Cu–TiO2/water hybrid nanofluid.

Efficiency analysis and operating condition optimization of solid oxide electrolysis system coupled with different external heat sources

Coupling external heat sources effectively reduces energy consumption and improves the efficiency of the solid oxide electrolysis (SOEC) system. While an in-depth analysis of the SOEC systems in different coupling scenarios is still needed. According to the internal heat demand and the temperature of external heat sources, three coupling scenarios are defined in this study, i.e., no heat source coupling (Scenario 1), coupled low-temperature heat source (Scenario 2), and coupled high-temperature heat source (Scenario 3). Firstly, the influence of critical parameters on system efficiency is analyzed from two perspectives, including specific system loss and specific energy consumption. The results present that efficiency η1 mainly increases with the rise of steam utilization. Efficiency η2 is not significantly affected by the parameters and is primarily positively correlated with the fuel electrode steam concentration. Efficiency η3 is negatively related to steam utilization, fuel electrode steam concentration, and fuel electrode flow rate, while positively to stack operating temperature. Meanwhile, for Scenarios 1 and 2, the exothermic state of the stack module should be avoided. Furthermore, the system performance maps and stack operating windows in the three scenarios are obtained by changing multiple operating parameters simultaneously and setting constraints. For Scenarios 1 and 2, high system efficiency, high hydrogen production, and long lifetime cannot be achieved simultaneously, so operating parameters need to be selected at a compromise. For scenario 3, high fuel electrode flow rate and low steam utilization can basically meet the above requirements. Both high stack operating temperature and high fuel electrode steam concentration can improve hydrogen production, while the former is mainly beneficial to efficiency η3, and the latter can improve the three efficiencies. The results obtained can be used not only to choose the optimal working conditions of various external heat sources but also to guide the online control and load regulation during system operation.

Multi-mode and exergoeconomic analysis of a novel combined cooling, heating, and power system applied in the geothermal field

The exploitation and utilization of geothermal resources contribute to alleviating energy crisis and reducing environmental pollution caused by the use of fossil fuels. The energy systems driven by low-grade geothermal heat sources also have the potential for energy-saving and emission reduction. Among all kinds of energy systems, multi-mode systems with characteristics of various operation modes and flexible energy output have been widely concerned. In this work, a multi-mode CCHP system with a novel structure is proposed and driven by a closed type of geothermal heat source. The proposed parallel system is composed of a vapor compression heat pump cycle, an organic Rankine cycle, and a vapor compression refrigeration cycle. The exergy efficiency and total product unit cost are selected as objective functions in multi-objective optimization processes to characterize system thermodynamic and exergoeconomic performances, respectively. The proposed system can operate in seven different modes to realize the conversion of power, heating, and cooling capacity output. The effects of main parameters, including evaporation pressure, condensing temperature, split ratio, etc, on system performances were studied. Results found that the coupling evaporator had the highest exergy destruction rate while the component turbine showed the largest capital cost. From the viewpoint of exergoeconomic performance, the turbine and coupling condenser were the most two important components. After that, the multi-objective optimization results revealed the limits of comprehensive system performance under such closed heat source conditions. Finally, the adjustable analysis found the performance range of the proposed system regulating the seven different operation modes. The exergy efficiency and total product unit cost fluctuated in the ranges of 18.68–52.64 % and 9.56–14.93 $/GJ, respectively.

Effect of CO2-based binary mixtures on the performance of radial-inflow turbines for the supercritical CO2 cycles

Recently, the supercritical carbon dioxide (SCO2) power cycle has become a hotspot in the field of energy-efficient utilization. The utilization of additives in the power cycle has been proven to be an effective way to improve the SCO2 power cycle efficiency. As one of the core components of the system, the influence of CO2-based mixtures on turbine performance needs to be further explored. In this study, the preliminary design and three-dimensional numerical simulation of a 500kW radial-inflow turbine (RIT) for small-scale SCO2 power systems were carried out. Furthermore, the design and off-design performance of high Reynolds number and small size turbine under the change of the CO2-based binary mixture compositions and mixing ratios were studied. Increasing the amount of nitrogen, oxygen, or helium into CO2 has a negative effect on the RIT performance, and the appropriate amount of xenon or krypton can improve the turbine efficiency. Moreover, mixtures with higher krypton additions adapt to higher heat source conditions. The loss of the turbine stage passage shows that a large amount of helium greatly reduces the working fluid density, and the high amount of xenon has a great influence on the dynamic viscosity, which all makes the RIT operation deviate from the steady state. Therefore, the CFD model simulation fails indicating that RIT designed based on pure CO2 may not run smoothly and continuously. The losses in the stage with pure CO2 and CO2–Kr mixture were investigated. The results indicate that the losses originated from the stator cannot be ignored and that the improvement of efficiency is mainly owed to the reduction in clearance losses. There is no doubt that the viewpoints proposed in this paper have significant reference value for the practical application of the SCO2 power cycle using mixtures.

Experimental assessment of an Organic Rankine Cycle with a partially evaporated working fluid

The Organic Rankine Cycle (ORC) has the potential to play a vital role in the mitigation of climate change by enabling low-temperature heat sources for power generation. This paper describes an experimental investigation of a variant of the ORC, known as the partially evaporated ORC (PEORC), and compares its power generating performance for a variety of heat source conditions to that of a conventional ORC. In contrast to the latter, the working fluid is only partially evaporated in the PEORC, which allows better matching of the temperature profiles of the heat source and working fluid during heat transfer.In the power cycle, the low GWP refrigerant R1233zdE was employed as working fluid. The mass flow and temperature of the heat source were varied from 0.25 to 0.35 kg/s and 110 to 140 °C, respectively. For each combination of heat source mass flow and temperature, the optimum operating point was identified by experiment in terms of exergy efficiency. Therefore, the evaporation pressure was varied in case of the ORC. In case of the PEORC, evaporation pressure and vapor quality at the evaporator outlet were varied. The results show that the PEORC outperforms the ORC in terms of exergy efficiency by up to 80 % for all investigated heat source conditions due to the much higher heat source utilization of the PEORC. The net thermal efficiency however is higher with the ORC due to the higher exergy level of the working fluid at the evaporator outlet.

Sizing optimization of thermoelectric generator for low-grade thermal energy utilization: Module level and system level

With the significant improvement of thermoelectric material properties, the thermoelectric generator is attracting more attention in heat recovery. The geometric parameters and design parameters have a significant effect on performance of TE module and system. Counterintuitively, for a fixed heat source condition, integrating more thermoelectric modules would reduce the overall economic performance, output power, and energy efficiency. In fact, there exists an optimal size of thermoelectric module number and geometry. In this study, a novel sizing method is proposed to find the optimal size parameters, which can be applied on both module and system levels. As a case study, exhaust gas from a truck engine of 708 K is considered as the heat source. Both technical constraints and economic indicators, such as NPV, IRR and payback period are analyzed. To maximize the TEG net present value, the optimal module height is found to be 1.5 mm and the module number is 144, under the studied thermal boundary condition. The analytical results in this study could provide guidance for thermoelectric generator system designs and help the realization of large-scale industrial applications.

Entropy production analysis of a radial inflow turbine with variable inlet guide vane for ORC application

The fluctuation of heat source conditions leads to the off-design operation and efficiency reduction of the radial inflow turbine (RIT). The adjustment of the outlet angle of inlet guide vane (IGV) is an important way to improve the turbine performance under off-design conditions. Since the energy dissipation caused by friction and flow separation is the main reason for the reduction of RIT efficiency, the entropy production analysis method is used to diagnose the location with high local energy loss in the RIT and evaluate its total energy loss under different working conditions in this paper. Firstly, an appropriate outlet angle of the IGV is determined according to the inlet pressure and outlet pressure of the RIT in organic Rankine cycle (ORC). Then, the effects of inlet pressure and outlet pressure on its energy loss are studied. The results indicate that the average entropy production rate (EPR) of the rotor in the RIT is the highest, which is mainly from the tip clearance and the inlet region. More than 70% of total entropy production of the turbine comes from the rotor, followed by the diffuser. The turbine can achieve lower total entropy production at higher outlet pressure or lower inlet pressure. Compared with a fixed IGV, the turbine with variable IGV can achieve higher turbine efficiency and output power under off-design conditions. The maximum increase in the efficiency and output power of the turbine with variable IGV under different inlet pressures is 3.8% and 12.9%, respectively.

Evaluation and Prediction of Formation of Heat-Affected Zone and Mechanical Properties According to Welding Method of STS 316L/A516-70N Clad Plates

Two welding methods of FCAW (Flux-cored arc welding) + FCAW, and FCAW + GTAW (Gas tungsten arc welding) were compared to identify effective routes for STS 316L/A516-70N clad stainless steel. Since the welding speed of the FCAW + GTAW welding method is slower than that of the FCAW + FCAW welding method, the amount of heat input is large, the size of the heat-affected zone formed is larger, and the amount of angular deformation is also large. The microstructure and deformation of the welding specimens were investigated by computational simulation, and the results were compared with calculated results for actual specimens. The results were very similar, thus confirming the high accuracy of the calculation. After measuring the hardness value of the actual welded specimens, the specimen welded by the FCAW + FCAW welding method was found to have a higher hardness value. The hardness of the welded portion of the FCAW + GTAW specimen tests tended to remain at nearly the same value throughout the specimen, indicating that the FCAW + GTAW hardness profile is desirable. In the computer simulation, butt welding was used to set the optimal heat source conditions for the two welding methods, and the effect of heat formed during welding was confirmed using the thermal analysis results according to the conditions. Based on the butt welding conditions, the residual stress and strain for the two welding methods are discussed, using calculations for the welding of C-seam (circumferential seam) and L-seam (longitudinal seam) used in the manufacture of pressure vessels.

Thermodynamic and exergoeconomic optimization of a novel cooling, desalination and power multigeneration system based on ocean thermal energy

For isolated islands and remote coastal and offshore areas, a multi-generation system based on ocean thermal energy conversion (OTEC) is one promising solution for electricity and water supply since it can exploit seawater resource and ocean thermal energy (OTE) simultaneously. In order to further improve the energy utilization efficiency, this paper proposes a novel combined cooling, desalination and power (CCDP) system consisting of open-OTEC cycle, dual-Kalina cycle, ejector refrigeration cycle (ERC) and reverse osmosis (RO) desalination. The integration of RO with OTEC can produce fresh water efficiently. A dual-pressure parallel Kalina cycle is introduced to utilize the ocean thermal energy in a stepwise manner. The adoption of an ejector can improve the power output. In addition, ERC is used to recover the exhausted heat from the turbine of the Kalina cycle. A detailed mathematical model is established, and a comparison with the stand-alone Kalina system under the same heat source conditions proves that the proposed CCDP system is more advantageous in terms of net power output, thermal efficiency and exergy efficiency. A parametric analysis is carried out with an emphasis on the effects of key parameters on the thermodynamic and exergoeconomic performance. Finally, a multi-objective optimization is executed based on non-dominated sorting genetic algorithm-II (NSGA-II). For the ammonia concentration of the basic solution, with the terminal temperature difference of vapor generator 2 and heat exchanger within the investigated range, there exist optimum values which can maximize the thermal and exergy efficiency and minimize SUCP simultaneously. Meanwhile, for the other five parameters, namely generation pressure 1 and 2, flash pressure1, the terminal temperature difference of vapor generator 1 and the evaporation temperature, there are trade-offs among the three performance indicators. The results suggest that the thermal efficiency (49.32%), exergy efficiency (50.08%) and SUCP (215.37 $/GJ) of the preferred optimal solution are improved by 7.43%, 9.87%, and 12.12%, respectively.

Operation strategy of a multi-mode Organic Rankine cycle system for waste heat recovery from engine cooling water

Engine cooling water contains a large amount of waste heat. Waste heat recovery (WHR) is a necessary way to improve the efficiency of engine. But too high or too low cooling water temperatures affect engine emissions and performance. To combine efficient WHR and rational use of waste heat from engine cooling water under variable engine operating conditions, this study proposed a parallel dual expander organic Rankine cycle (ORC) system that can operate in multiple modes. To exploit its advantages, the system characteristics were explored and a system operation strategy was developed through experimental studies. The regulations of the system operation were summarised through extensive experiments exploring system performance. Four system operation modes were developed based on these regulations. The four modes are applied to different heat sources to meet heat exchange requirements while operating efficiently. Finally, the feasibility of this operating strategy was verified by experiments under 16 sets different heat sources. Results show that the ORC-WHR system and operating strategy can effectively adapt to the heat source variation. The parallel operation of the dual expanders can broaden the applicable heat source conditions by 120%. This study provides the basis for the practical application of this system.

Thermo-economic analysis of a hybrid system based on combined heat - isobaric compressed air energy storage and humidification dehumidification desalination unit

To solve the problem of electricity and fresh water supply in different low-efficiency independent systems in coastal areas or remote islands, a hybrid system based on energy cascade utilization principle is proposed for both small-scale electricity and fresh water supply purposes. Such hybrid system is made up by the combined heat - isobaric compressed air energy storage (CH-ICAES) and the water-heated humidification dehumidification (HDH) desalination unit. Meanwhile, the CH-ICAES is a synthesis of ICAES and power to heat (PtH) technologies. In operation, the low-grade heat from CH-ICAES charging and discharging is used to produce fresh water in HDH. The simulated results show that the gained-output-ratio (GOR) and total produced fresh water mass in a roundtrip cycle at design condition are 2.0678 and 851.77 kg, respectively. Meanwhile, the levelized cost of storage (LCOS) and levelized cost of water (LCOW) are 35.45 cents/kWh and 0.57$/ton, indicating a competitive economic performance. Moreover, the GORs in charge and discharge are different due to the non-uniform heat source conditions. In addition, the humidifier inlet seawater temperature, the effectiveness of humidifier and dehumidifier, the relative humidity of dehumidifier inlet air, the HDH operation pressure and some parameters of CH-ICAES have significant effect on hybrid system performance.

Effects of copper and titania nanoparticles on MHD 3D rotational flow over an elongating sheet with convective thermal boundary condition

Copper nanoparticles (NPs) are used as highly thermal conductive material as well as alloys. In the same way, titanium dioxide nanoparticles have wide usage in coating, waste water treatment, food industries and space crafts etc. The three dimensional (3D) rotational nanofluid flow and heat transfer over an elongating sheet with thermal radiation, heat source and thermal convective boundary condition is studied. The convective heat transfer currently discussed is the superposition of thermal conduction due to temperature gradient and heat energy transfer by the flowing fluid. This phenomenon has been combined with electrically conducting nanofluid subjected to magnetic field. Further, flow model includes rotation and translation which find applications in chemical and process industries. The boundary conditions on heat transfer involves Biot number (Bi) which is important because most of the problem reported in literature involves Nusselt number which is a relative measure of heat transfer coefficient and thermal conductivity, both related to flowing fluid. The solution involves Runge-Kutta forth order method with MATLAB code. It is found that for metallic nanofluid (Cu) temperature remains positive and for metallic oxide nanofluid (TiO 2) the temperature remains negative, indicating thermal energy generation and absorption due to metal or metallic oxide as nanoparticles.

Isogeometric and NURBS-enhanced boundary element formulations for steady-state heat conduction with volumetric heat source and nonlinear boundary conditions

Boundary Element Method (BEM) is a numerical tool that is applied to many different types of engineering problems. BEM possesses several advantages over other numerical methods such as boundary-only discretization and its semi-analytical nature. Application of Isogeometric Analysis (IGA) to BEM is a recently proposed computational method where the main purpose is to use geometrical basis functions as the shape functions of field variables. Key features of combining these two techniques are the exact representation of the geometry, elimination or suppression of the meshing procedure, reduction of the problem dimension and obtaining highly accurate results especially for the flux values on the boundaries compared to conventional BEM. In this study, steady-state heat conduction problems with nonlinear boundary condition and surface heat source are analyzed where geometries are formed by NURBS, and field variables are described with Lagrangian (constant and quadratic) basis functions and NURBS basis functions. Convergence rates and CPU time of different types of element representations are discussed which eventually reveals the performance and capabilities of IGABEM.

Uniforming thermal distribution by air-convection aspirated in partially hollowed tetrahedral lattice porous cold plates for the drone battery

A pouch-type lithium-ion battery requires effective thermal management and a solution for temperature imbalances depending on its morphological characteristics. In this study, we present such a solution for rows of pouch-type lithium-ion battery cells controlled by aspirated air convection in a tetrahedral lattice porous cold plate, as well as by reducing the temperature imbalance in the lattice porous medium (LPM). The hollowness ratio (HR) was applied to the ligament, and its effect was investigated in the entrance region of the cold plate channel. A series of steady-state numerical simulations and experiments were conducted to demonstrate the effectiveness of the solution. As a result, the temperature deviation in the longitudinal direction of the LPM cold plate's lower substrate was 6.4°C under the 7 C-rate heat source condition. Owing to the inlet effect of forced convection due to the aspirated airflow, the lowest temperature was observed on the inlet side, and a higher temperature was observed on the outlet side. By applying the HR to the ligament of the LPM cold plate, it was confirmed that the temperature deviation decreased to 4.4°C, which was 2°C lower than that applied to the simple solid ligament. In addition, the temperature uniformity index (TUI) was 0.96, when the hollowness ratio was 0.64.

Theoretical investigation of hybrid nanomaterials transient flow through variable feature of Darcy–Forchheimer space with exponential heat source and slip condition

Nanomaterials have achieved remarkable importance in cooling small electronic gadgets like akin and microchips devices. The role of nanoparticles is essential in various aspects, especially in biomedical engineering. Thus hybrid nanomaterials is introduced to strengthen the heat exchangers' performance. In view of the above practical and existing applications of nanomaterials. Our aim is to examine the consequences of Darcy–Forchheimer's radiative and Hall current flow of nanomaterials over a rotating porous disk with variable characteristics. Stretching disk accounting for the slip condition. Nanoparticles ZnO and CoF2O4 are dispersed in based fluid water. The present model is utilized for thermo-physical attributes of hybrid nanomaterials with the impact of shape factor. Transformations convert the modeled PDEs into ODEs. The obtained highly non-linear system is tackled numerically by the NDSolve technique through the software Mathematica. The outcomes of significant variables against different profiles are executed and elaborated in detail. Obtained results show that both nano and hybrid nanofluid radial velocity have reverse behavior against variable porosity and permeability parameters, whereas it decays for larger Forchheimer numbers. Further, it is worthy to point out that, hybrid nanophase has a higher impact on distinct profiles when compared with nano and common liquid phases.

A partial heating supercritical CO2 nested transcritical CO2 cascade power cycle for marine engine waste heat recovery: Thermodynamic, economic, and footprint analysis

A novel cascade system, in which the exhaust CO2 residual heat from a partial heating supercritical CO2 (SCO2) power cycle is reclaimed by a transcritical CO2 (TCO2) power cycle, is developed for onboard engine exhaust gas waste heat recovery. Firstly, thermodynamic analysis of the cascade system is carried out with the investigation of pinch points in heat exchangers. Then the influence of the topping cycle on the heat source condition of the bottom cycle is found, and the parametric study of the cascade system is performed from the viewpoint of thermodynamics, economy, and footprint. Further, the system comparison analysis with single-optimization is carried out to prove the superiority of the proposed system. Finally, the three-objective optimization is performed to maximize power output, minimize heat exchanger area per unit power and levelized cost of electricity. The results indicate that by integrating a TCO2 power cycle with the partial heating SCO2 cycle, system thermodynamic performance can increase by 15.35%. The recuperator effectiveness has a great impact on the bottoming cycle heat source temperature. The total heat recovery efficiency of the proposed system is improved by 22.64% and 20.24% respectively, compared with the simple SCO2-TCO2 combined cycle and the recuperative SCO2-TCO2 combined cycle. The multi-objective optimization results of the system performance are 841.84 kW, 0.2028 m2/kW, and 7.434 cent/kWh, respectively, with the 136 °C discharge temperature of the exhaust gas and 29.26% thermal efficiency. These results confirm the cascade system is attractive to waste heat recovery engineering, especially in space-constrained applications.

Optimal design of dual-stage combined cycles to recover LNG cold energy and low-temperature waste thermal energy for sustainable power generation

To overcome the shortcomings of the low net power output of a single power generation cycle for LNG cold energy recovery, investigating dual-stage combined cycles with different cycle configurations under the same heat and cold source conditions is mandatory. Hence, this study proposes 12 dual-stage combined power generation cycles to utilize LNG cold energy and low-temperature (below 200 °C ) waste thermal energy. The developed method adopts an organic Rankine cycle and Brayton cycle as the bottoming cycle and the organic Rankine cycle, Brayton cycle, and supercritical carbon dioxide power cycle as the topping cycle with parallel and serial configurations. The optimization results show that the thermodynamic and economic performance are compared quantitatively. The optimally combined cycle is a dual-stage serial organic Rankine cycle with the highest specific net power output of 202.15 kJ/kg and lowest levelized cost of electricity of 0.11 $/kWh. Regarding the parallel configuration, it can enhance thermal and exergy efficiency via its internal heat integration. Moreover, the evaporation and condensation pressure of the bottoming cycle has a more significant influence on the optimally combined cycle than the topping cycle. Overall, this study paves the way to design economics-efficient dual-stage combined cycles for sustainable power generation by utilizing LNG cold energy and low-temperature waste thermal energy.

Thermal constriction resistance of an axisymmetric plate subjected to a circular heat source and mixed boundary conditions. Semi-analytical solutions and simple and accurate correlations

This article deals with a complex problem of thermal constriction induced by mixed boundary conditions. Recently (Laraqi et al., 2021) [1], we have developed a set of new analytical solutions to solve some thermal constriction problems for the particular case of semi-infinite axisymmetric media under mixed boundary conditions. In this article, we propose a study extended to media of finite thickness to cover other applications related to thermal problems such as electronic cards equipped with chips, and other assemblies involving thin plate. The problem of finite thickness is much more complex to solve. In this article we consider a plate subjected to a circular heat flux density while the rest of the same face is isothermal. Two configurations concerning the rear face are studied. In the first one the surface is adiabatic and in the second one it is isothermal. The analytical developments are carried out until obtaining a Fredholm integral equation of the second kind with finite limits and explicit and converging kernel. Its resolution is done numerically in an easy way (a simple linear system to solve). Comparison with some available results is performed and shows an excellent agreement. Furthermore, on the basis of a judicious study of the asymptotic behavior, simple and accurate correlations are proposed to calculate the thermal constriction resistance for the both considered configurations.

Three-dimensional numerical analysis of flow and heat transfer of bi-directional stretched nanofluid film exposed to an exponential heat generation using modified Buongiorno model

The heat transfer characteristics of copper/water nanofluid flow over a bi-directional stretched film are theoretically studied. The used mathematical model accounts for nanofluid effective dynamic viscosity and thermal conductivity. The model of the current study utilizes the modified Buongiorno model to scrutinize the effect of haphazard motion, nanoparticles' thermo-migration, and effective nanofluid properties. 3D flow is driven by having the nanofluid film elongation in two directions. The thermal analysis of the problem considers the nonlinear internal heat source and Newton heating conditions. In modeling the problem, the Prandtl boundary layer approximations are employed. Moreover, the nonlinear problem set of governing equations for investigating the transport of water conveying copper nanoparticles was non-dimensionalized before being treated numerically. The current parametric study investigates the impact of governing parameters on nanoparticles velocities, temperature, and concentration distributions. The presence of copper nanoparticles leads to a higher nanofluid temperature upon heating. The temperature enhances with the nanoparticles Brownian movement and thermo-migration aspects. Furthermore, involving a heat source phenomenon augments the magnitude of the heat transfer rate. Moreover, the velocity ratio factor exhibits decreasing behavior for x-component velocity and increasing behavior for y-component velocity. In conclusion, the study results proved that for larger values of Nb and Nt the temperature is higher. In addition, it is clear from the investigations that the Lewis number and Brownian motion factor decline the nanoparticle concentration field.

Development of Design Method for River Water Source Heat Pump System Using an Optimization Algorithm

River water source heat pump (RWSHP) systems are being proposed to reduce the energy consumption and carbon emissions of buildings. The RWSHP system is actively applied to large-scale buildings due to its stable performance. The application of RWSHP in large-scale facilities requires an accurate capacity design with considerations of building load, heat source, and environment conditions. However, most RWSHP systems are over-designed based on peak load of buildings. These design methods, based on peak loads, are economically and environmentally disadvantageous. Therefore, this paper aims to development an optimal design method, both economically and environmentally, for the RWSHP system. To develop this optimal design method, a simulation model was created with an optimization algorithm. The economics of the RWSHP system were calculated bases on present worth of annuity factor. Moreover, CO2 emissions were estimated using the life cycle climate performance proposed by the International Institute of Refrigeration. The total cost of the proposed RWSHP system that apply the optimum design method decreased by 24% compared to conventional RWSHP systems. Moreover, CO2 emissions of the proposed RWSHP system reduced by 4% compared to conventional RWSHP systems.