This paper describes the measurement of convective heat transfer coefficients and friction factors for sCO2 flowing in additively manufactured tubes with internal pin fins at the US DOE’s National Energy Technology Laboratory in Morgantown, WV. The measurement procedures were validated by conducting benchmark tests with smooth stainless-steel tube and comparing the results with published correlations

Natural Convective Heat Transfer Characteristics in a cavity filled with a porous medium as related to a solar collector was studied numerically in this investigation. The effect of adding porous medium, obstructed object, and flexible wall on heat transfer performance inside the thermal system was analyzed for different variables such as Rayleigh number, location of the obstructed cylinder, effective

Compared with two tank thermal energy storage (TES) system, the single-tank thermocline (STTC) TES system provides a more cost-effective option for TES systems with low-cost solid filler, and it is progressively becoming an important research topic. In this study, analytical approach solutions derived from the one-dimensional two-phase (1D-2P) without heat loss model and one-dimensional one-phase (1D-1P)

Direct-expansion solar-assisted heat pump water heaters (DX-SAHPWHs) are conducive to the environment due to the use of ambient energy and solar radiation. This paper aims to design and develop a thermodynamic model and a multi-criteria optimization of thermal performance for a DX-SAHPWH using R-134a as the working refrigerant that supplies domestic hot water for a typical building throughout the whole

A multi-criteria assessment of a solid oxide fuel cell (SOFC)-based polygeneration is presented. Taking a residential area in Malaysia as the case study, the polygeneration is integrated with the photovoltaic thermal and thermoelectric generator as the most applicable heat recovery devices to be combined with a solid oxide fuel cell (SOFC). The proposed recovery system is compared with the basic heat

The battery energy storage system (BESS) is widely used in the power grid and renewable energy generation. With respect to a lithium-ion battery module of a practical BESS with the air-cooling thermal management system, a thermofluidic model is developed to investigate its thermal behavior. The thermal model for a single battery is established and experimentally validated first, and then the thermofluidic

Conventional hybrid absorption-compression heat pumps are difficult to efficiently upgrade waste heat to a heating temperature of above 90 °C. In this paper, to solve this problem, two novel approaches, namely a two-stage rectification and a subcooler, are specially proposed for the hybrid heat pump. By designing a two-stage rectification to reduce the suction temperature of compressor, thereby lowering

Heat transfer characteristics in cryogenic oscillating flow is essential to the development of high-efficiency cryocoolers. In this study, the heat exchanger performance in cryogenic oscillating-flow conditions was experimentally studied. Based on the collected experimental results and the material properties that can affect the targeted space-cycle averaged Nusselt number, machine learning models

The refrigerant generating bubble pump, in which the generation of refrigerant vapor and the pumping of solution both take place, is used to transport refrigerant, absorbent and diffusion gas in a diffusion absorption heat transformer. In this paper, experiments of refrigerant generating bubble pump were performed with H2O (water) as refrigerant, HCOOK (potassium formate) as absorbent and air as diffusion

A theoretical analysis of the energy efficiency of a direct contact membrane distillation (DCMD) module with external heat recovery intended for desalination applications is carried out. A porous media model is proposed and validated against previously reported numerical and experimental results. A 2n planning scheme is employed to determine the most decisive membrane properties for maximizing the

Exhaust gas recirculation (EGR) is widely used in most current automotive diesel engines as a simple, economical, and highly effective NOX reduction technology. The low pressure (LP) loop EGR has higher deNOX efficiency, but also has problem of water condensation, which causes wear of the turbocharger compressor wheel, and corrosion or freeze rupture of intake components. Using a one-dimensional engine

The flashing flow is a relevant multiphase phenomenon in many technical applications including nuclear safety analysis, which has been the subject of intense research for several decades. Numerical studies have evolved from one-dimensional to multi-dimensional. A variety of methods has been proposed, while a broad consensus does not exist yet. The present work aims to present an overview of available

In this study, a novel cooling strategy based on setting spoilers in the airflow distribution plenum of a parallel air-cooling model was proposed to improve the cooling performance of a battery cooling system. In combination with the computational fluid dynamics (CFD) method, the effects of the number and position of spoilers on the thermal behaviors of a battery thermal management system (BTMS) were

The two-phase thermosyphon loop (TPTL) has been widely used in data center cooling. But there is no practical design method and quantitative guidance to ensure a well-designed TPTL. In this paper, the approaching degree to “ideal cycle” ɛ is adopted as the efficiency indicator, based on which, a practical design method for TPTLs used in HVAC is proposed, ensuring the efficiency as well as the capacity

The output characteristics of single screw expander has a direct and crucial influence on the performance of vehicle ORC system. In this paper, a machine learning prediction model driven by experimental data is developed and applied to predict the power output of single screw expander. After screening different structural parameters of the model, GA is used to optimize the initial weights and thresholds

This work primarily focuses on designing a cost effective method yielding high rate of heat transfer from a heated object to ensure the faster melting of the phase change material (PCM). A numerical investigation has been performed on the laminar natural convection from a two-dimensional heated circular cylinder confined in a square enclosure filled with a phase change material, namely, the lauric

Large eddy simulation is performed to investigate the mixing characteristics between the hot and cold fluids in a T-junction with different amplitudes and periods of inlet velocity. The distributions of temperature field and velocity field as well as the properties of vortex structures are focused in the present study. In addition, the wavelet power spectrum density (WPSD) of both temperature and velocity

As awareness on air pollution in marine environment increases, transition of ship fuel to natural gas has been recognized as a practical solution for emission minimization. It is realized with LNG-fueled ship, whose implementation in practice demands cost-effective and energy-efficient re-liquefaction of BOG. The purpose of this study is to introduce precooling cycle to BOG re-liquefaction process

In order to better reflect the actual heat transfer process, the heat transfer process of the gas jet matrix impact cooling strip steel was studied by the experimental method, and investigated the effects of jet Reynolds number Re, dimensionless nozzle spacing Χn/D (the ratio of the orifice spacing to the orifice diameter), dimensionless jet height H/D (the ratio of strip to orifice distance to orifice

Fault detection (FD) for building energy systems in the presence of missing data is discussed in this paper. The purpose is to propose an enhanced FD method with higher accuracies under both missing univariate data and multivariate data. The solution is to develop an effective missing data imputation model with low complexity and high computational efficiency to impute the missing values. An FD method

R410A is a widely used refrigerant in residential liquid-to-water heat pumps. Variable speed compressors and electronic expansion valves are known to increase the heat pump performance and are becoming a common option in high efficiency heat pumps. Additionally, in order to minimize the system dimensions and the refrigerant charge, many domestic heat pumps are produced without liquid receivers. These

Conjugate heat transfer analyses of methane/air premixed flames propagating toward walls are performed without employing any wall model in terms of one- and two-dimensional numerical simulations, and the flame-wall interaction is investigated in detail. To describe the combustion reaction of methane, a two-step global reaction model is used. In one-dimensional numerical simulations, the effects of

Gas quenching dry slag granulation process is an energy-saving environmental protection method for waste utilization and waste heat recovery of molten slag, and the molten slag is broken up by supersonic airflow into droplets in this process. This paper performed the numerical investigations on the breakup behavior of slag by the coupled level-set and volume of fluid (CLSVOF) methodology and gain a

A novel double-effect/two-stage compression-assisted absorption thermal energy storage system using LiNO3-[BMIM] (1-butyl-3-methylimidazolium) NO3/H2O for combined cooling and heating is proposed to enhance thermal performance under a larger concentration glide without crystallization. The thermodynamic calculation is conducted by Matlab based on the measured thermophysical properties, and its performance

In this work, a novel integrated system based on a combination of solid oxide fuel cell (SOFC) with compressed air energy storage (CAES) and turbocharger is presented for simultaneous production of domestic hot water and power in the scale of retail buildings for peak shaving applications. The SOFC subsystem is the primary power generation unit, which is coupled with CAES and other supporting auxiliary

Evaporation of flowing propane and the effect of enhanced geometry on heat transfer coefficient and pressure drop is experimentally investigated. One smooth tube and two microfinned tubes with an outer diameter of 5 mm were tested. Heat transfer coefficient and pressure drop were determined for saturation temperatures of 0, 5 and 10 °C for smooth tube, and the effect of using tubes with enhanced geometries

Humidity is one of the important climate parameters in greenhouse food production. Maintaining humidity levels within the optimal growth range enhances yield. Moreover, excessively high relative humidity leads to diseases and deterioration of the crops. This paper presents a state-of-the-art review of the various dehumidification technologies available in the agricultural industry. Several novel conceptual

This study reports specific heat transfer figures of merit for thermal regenerators and applications using the passive characterization, which can rapidly predict the cooling capacity of active magnetic regenerators (AMRs) in magnetic refrigeration. We expand the expression for the thermal effectiveness in terms of the individual contributions of heat storage and parasitic losses, using one-dimensional

This paper presents a new fin pattern for air-cooled branched-wavy minichannel heat sink (BWMCHS) where three different secondary passes at a distance of 0.5λ, 1.0λ and 1.5λ have been considered (λ is the wavelength and equals to 20 mm). A comprehensive computational and experimental analysis is implemented to investigate the thermo-fluidic characteristics in detail. The RNG k-ε model with enhanced

The thermal characteristics of batteries in electric vehicles are important for the vehicle performance and safety. In this work, various battery thermal management methods for laminated lithium-ion batteries are evaluated by experiments and numerical simulations. First, a simulation scheme is proposed and verified by the results of the experiments conducted in this study. Then, five thermal management

In this study, a comprehensive mathematical model of a thermoelectric infant incubator operating with modular thermoelectric heat pump system (MTEHPS) was developed. All heat and mass exchange processes of the thermoelectric infant incubator system with both the premature infant and the surrounding atmosphere were determined and modeled. For that, the system was divided into 8 sub-compartments. Mass

This study proposed an improved CO2 heat pump system for electric vehicles by introducing the concept of two stage compression with intermediate cooling. A coefficient of performance optimal control strategy was proposed based on the discovered feature that the changing trend of the COP is consistent with that of the inlet temperature of the electronic expansion valve. Contrast experiments between

The topic of boiling heat transfer in miniscale geometries has focused the ever increasing interest of researchers in recent years. However, most of the works are related to mini- and microchannels and much less to minigaps. Meanwhile, minigaps allow for more comprehensive experimental studies, i.e. flow visualisations due to the flat, two-dimensional configuration of the flow. The results of the experimental

In port areas, with the progressive increase in maritime traffic, the problem of pollution is crucial especially when the port is near to an urban area. The cold ironing allows a reduction of pollutants satisfying the power demand of ships while they are at berth, replacing on board diesel engines. In this paper, the methodology of analysis of the electrical loads required by ships concerns the typical

The effects of a late intake valve phase (LIVP) strategy on crank-angle resolved real-time turbocharger efficiency were analyzed. The research is composed of experiments and simulations. In the experiments, an engine test was conducted with a downsized 2.0 L 4-cylinder turbocharged-gasoline direct injection (T-GDI) engine. In order to evaluate the effects of LIVP on the instantaneous turbocharger efficiency

This work is concerned with an experimental investigation of the thermal performance of two thermoacoustic heat exchangers characterized by different pore geometries, namely a circular-pore geometry and a finned-tube geometry. A standing wave engine, where the heat exchangers under test play the role of ambient HXs, is used as test-rig. Heat transfer rates measurements by standard energy balance techniques

The parameter variation, condensation and distribution of wet steam are very complicated when the steam turbine works under small flow rate condition. In this paper, the two-phase fluid model, the homogeneous nucleation model and the droplet growth model are combined to study the parameter variation in the last stage flow field, the condensation and distribution rule of wet steam and the interaction

The operating temperature rise and the dust accumulation on the front side of solar panels especially in arid and semi-arid desert areas is a major issue that causes low performance and damage to photovoltaic cells. This experimental investigation aimed to improve the solar panel electrical performance mounted in new hybrid system PV/T Bi-fluid that combines both active cooling and self-cleaning technique

This paper presents an ultrasonic mist generator used as an evaporative pre-cooler for air-cooled condensers in air conditioning applications. Ultrasonic mist generators eliminate pressure loss at the inlet air stream to the condenser and allow controlling the characteristics of the water atomized droplets. A water mist generation unit has been designed, built, and tested to assess its thermal performance

Laminated cooling coupled by surface thermal barrier coating (TBC) has a large potential to provide the effective protection to components in next-generation gas turbines. However, the conjugate heat transfer characteristics of coupling system is reported rarely. In this work, the combined effects of internal element layout, coating thickness and cooling air amount on the metal and TBC surface temperatures

After evolving side by side over the past three decades, insulated gate bipolar transistors (IGBTs) and metal–oxide–semiconductor field-effect transistor (MOSFETs) become two main options in high power semiconductor market of Hybrid Electric Vehicle (HEV) or Battery Electric Vehicle (BEV) systems. Recent improvements on high power performance are focused on the reduction of power losses and the enhancement

In the present study, a cylindrical superheater for producing high-temperature superheated steam was installed in a furnace, and its heat flow characteristics were investigated. The effect of applying circular fins of various curvature angles to the inside of the superheater was analyzed to improve heat transfer performance. The steam flowing into the cylindrical superheater showed a swirling flow

To accelerate the start-up period of Gatton NDDCT, windbreak walls are introduced under the heat exchanger inspired by theoretical analysis, which suggests quicker start-up with increasing values of β, which is a factor that represents the proportion of crosswind redirected into the tower via the heat exchanger by windbreak walls. Three-dimensional (3-D) numerical models at three different wind angles

Owing to the complex mesoscopic structures, 3D braided charring composites for the thermal protection system (TPS) have the multi-scale and multi-physical high-temperature responses. The mesoscopic features can significantly affect the volumetric ablative behavior of the braided composites, which will be essential for the TPS design. To take into account the effect of mesoscopic structures on the volume

Reducing wall temperatures is a promising method to suppress knocking behavior in spark-ignited engine. However, this may increase undesirable heat loss which acts as countereffect, so a strategic cooling approach is required. In this study, a multidisciplinary investigation of the wall temperature effect was demonstrated using experiments and simulations. By experiments under full load and part load

A numerical analysis of pressure drop and heat transfer for open-cell porous media is performed using a three-dimensional conjugate heat transfer model. Porous metal with a pore density of 20 pores per inch (PPI) and porosity of 95.7% is used in the present numerical simulation. Real microstructure of the open-cell porous metal is constructed using stacked images obtained by X-ray computed tomography

As a technology of the green energy utilization, solar adsorption cooling is a promising way to make use of the solar energy in the future. Aiming to the efficiency improvement of such kind system, the performance of the solar adsorption cooling system that employed the silica gel-water as the working pair was evaluated experimentally. With a mono-axial solar collector of tracking parabolic trough

A new submillimeter-thick loop heat pipe (LHP) fabricated using two copper sheets is proposed as a cooling solution for thermal management of electronics. The experimental investigation was conducted by measuring the temperature of each part of the surface of the thin LHPs for its heat input, to evaluate the heat transport characteristics of the LHPs discussed in this paper. Submillimeter LHPs with

Moist air condensation is of significant scientific and societal interest especially for harvesting potable water from atmospheric air. Dropwise condensation of water vapor present in moist air is preferred when compared to filmwise condensation because of high transport coefficients that augment condensation rate of the distillate. The efficacy and sustainability of dropwise condensation depends on

Two-phase ejectors are used in the refrigeration cycles to decrease the throttling losses and improve the performance. The subject of this paper is the motive nozzle which is the critical component of the ejector since the pressure distribution throughout the motive nozzle affects the secondary fluid to be entrained into the ejector. A simplified version of the one of the previously established one-dimensional

This study investigates the prediction of the combustion process using an artificial neural network (ANN), and an efficient prediction methodology is introduced. In particular, the conditions for using hydrogen as an additive to a turbo-charged gasoline direct injection (T-GDI) engine are discussed. Research to predict the physical phenomena using ANNs has been actively conducted for various applications

This paper numerically investigates the thermal performance and stress analysis of enhanced Copper (Cu) spreaders for nucleate boiling immersion cooling of high-power electronic chips. The proposed spreaders take advantage of the remarkably high thermal conductivity of Cu (low thermal spreading resistance) and enhanced nucleate boiling heat transfer of dielectric liquid PF-5060 on Microporous Cu (MPC)