This work presents the design, optimization, and a comparative study of a compound parabolic concentrator (CPC) using a tube as a receiver with and without a fin inverted V-shaped receiver (finned receiver). The study was mainly based on numerical analysis obtained by using a ray-tracing simulator in CPCs, in order to evaluate the amount of solar irradiation collected on four dates of the year. A north-south

In the framework of building of a new eco-neighborhood in Grenoble, France, an innovative urban heating network is under construction, which seeks to couple a low temperature substation (47°C – 72°C), a 200m2 solar thermal field, a 180kWh Phase Change Material (PCM) heat storage unit (based on a tube and shell assembly), and a smart management system. This paper focuses on the design and preliminary

To optimize the plate-fin heat exchangers in the cryogenic processing system, the heat transfer characteristics of two-phase flow boiling for high-efficiency and pressure-resistant offset strip fins in plate-fin heat exchangers were investigated experimentally. The experimental conditions cover heat fluxes of 0.7-5.5 kW/m2, mass fluxes of 64∼128 kg /(m2·s) and vapor qualities of 0.1∼1.0. The research

High flow resistance in conventional porous regenerators has been an important factor for limiting the overall performance of Stirling engines. Herein, a novel constructal bifurcation regenerator based on constructal concept was developed to reduce the flow resistance in the Stirling regenerator. First, the pressure drop and transient conjugate heat transfer characteristics of oscillating flows through

In this paper, a novel determination method of defrosting start time based on frost accumulation amount tracking (FAAT) is proposed for air source heat pump systems. This method keeps tracking of the amount of newly deposited frost every time step using typical sensors adopted in the commercial heat pump systems. This is to predict the current volumetric blockage ratio in real-time and determine the

To meet the urgent requirement of high heat flux cooling of the chips in current electronic equipment, a unique and reliable U-shaped heat pipe bonded heat sink was developed and experimentally investigated for CPU cooling in computers. This novel heat sink was bonded with air-cooled fin stacks and two U-shaped heat pipes through the base plate. In this work, the effects of relevant parameters, including

Heat recovery from local resources is shown to be a promising solution to reduce the carbon footprint of district heating. Supermarkets equipped with a CO2 refrigeration system and a geothermal storage offer a larger heating capacity, compared to traditional solutions. While district heat could benefit from this higher heat recovery availability, supermarkets could generate an income from a capacity

Film cooling performance on the twist turbine blade leading edge (LE) model has been experimentally investigated employing the thermochromic liquid crystal (TLC) technology under rotation conditions. The novelty of this paper is the earlier study on the effect of film hole diameter (d = 0.4 mm and 0.5 mm) on the LE region of a rotating twist blade. The effects of blowing ratio (M) and density ratio

This paper reports both experiments and analyses of supercritical CO2 in two heated vertical parallel channels. The intent of the present experiments was to search for static instability in an up-flow system. However, no static instability was found using CO2. A total of 18 experiments at different flow conditions were performed with supercritical CO2 flowing upwards. Eleven were already published

Flow boiling heat transfer tests were conducted to evaluate the Critical Heat Flux (CHF) and Heat Transfer Coefficient (HTC) of conventional and accident tolerant fuel (ATF) cladding materials, i.e., bare Zircaloy-4 (Zr4), and Zircaloy-4 coated with Chromium using physical vapor deposition (PVD) (Zr4-Cr-PVD) and cold spray process (Zr4-Cr-CS), respectively. The tests were performed on a single heater

This paper seeks to develop a mathematical model to analyze a novel ejector enhanced heat pump system from the thermodynamics viewpoint, and optimize the system by an elitist multi-objective non-dominated sorting genetic algorithm (NSGA-II). Zeotropic mixture (R600/R143a) is used as the system working fluid, and a booster is added to the conventional ejector enhanced system to improve the coefficient

The energy associated with clothes drying makes up 4% of the total residential electrical energy consumption in the US. The cost is high since most clothes dryers use electric resistance heating which is inexpensive but also energy inefficient. State-of-the-art vapor-compression heat pump clothes dryers offer significant energy savings but have limited market penetration in the US. In this work, a

Reducing mass and size characteristics of heat and mass exchangers requires intensifying the heat and mass transfer processes inside them. The authors propose improving the performance of adiabatic evaporators by placing a packing made of capillary-porous material into the working chamber behind the nozzle. This packing is designed as a system of parallel channels positioned at an angle to the axis

The use of ground source heat pump systems (GSHPs) with tunnels (so-called energy tunnels) to provide space heating and cooling is one of the latest concepts that has recently raised research interest but has not yet been commercially established. This study represents the first attempt to investigate the influence of design parameters on the energy efficiency of a GSHP using an underground tunnel

This paper presents a transient heat and mass transfer model with experimental validation of a finned cylindrical adsorbent bed for performance analysis in chemisorption refrigeration system. The approximate solution for the mathematical model, including transient heat and mass transfer equations in cylindrical coordinates, was obtained by implementing the Crank-Nicholson approach in a finite difference

This paper compared the performance of solar photovoltaic/thermal (PV/T) air collectors (SPVTAC) based on amorphous silicon solar cells with traditional solar air collectors and individual photovoltaic (PV) modules. The SPVTAC was proposed to overcome the problems of large thermal stresses at fluctuating temperatures and frost in winter, and also due to their working suitability in medium-high temperature

In order to maintain the proper operating temperature and avoid thermal runaway propagation of lithium-ion power battery module, this paper proposes a novel hybrid battery thermal management system based on phase change material (PCM) and liquid cooling. In the proposed system, the operating temperature of the battery is maintained mainly by latent heat of PCM. In the case of thermal runaway condition

A method that combines VOSET and IDEAL was previously presented by the present authors for computing incompressible two-phase flow and heat transfer problems. The technique could provide an accurate calculation of a high-resolution phase interface. However, this method still has a considerable computational burden for complex transient two-phase flow and heat transfer problems. Therefore, to further

High-performance thermal management devices require both high heat flux and high heat transfer coefficient (HTC). Boiling heat transfer provides an effective way toward these goals by utilizing the large latent heat of vaporization. However, HTC of typical pool boiling is hindered by thick liquid layer with relatively slow bubble dynamics. We recently demonstrated a “thin film boiling” mechanism that

High cell temperature of PV modules would reduce electrical efficiency and hinder the development of photovoltaic application. Many potential cooling channels have been proposed for PV modules cooling but perform inefficiently, due to the insufficient heat transfer between the cooling water and PV modules. In current research, a PV/T system with a special cooling channel based on field synergy theory

A free piston Stirling engine is a complex system that its transient behaviors of thermal properties and dynamic characteristics are coupled with each other. In order to assess the performance of the engine, the prediction of the aforementioned properties becomes unavoidable. In this study, a modified non-ideal adiabatic model and a dynamic model were solved simultaneously for determining the thermal

Thermal power plants experience cycling duty leading to the fatigue of the boiler and heat exchanger tubes. As a result, tube failures occur frequently in coal fired fleets leading to forced outages. Because the tube leaks have been the major source of unwanted shutdowns and the number of outages is increasing, present work focuses on the detection and isolation of the leak in a subcritical boiler

Nowadays, lithium-ion battery (LIB) technology provides one of the most important approaches for large-scale electricity storage. In this work, an electrical-thermal-fluidic coupled model is proposed for practical LIB-based energy storage systems (ESSs). The coupled model is established based on the equivalent circuit model (ECM) which describes electrical behavior of LIBs, the airflow turbulent model

A cryogenic loop heat pipe (CLHP) is an effective means of temperature control at low temperatures, but the physical properties of cryogenic working fluids are quite different from those of room-temperature working fluids, and their phase change and heat transfer characteristics need to be further studied. In this paper, a test system for evaluating the loop heat pipe (LHP) heat transfer performance

There is not a specific technical proposal to be able to achieve a clear presentation of the complex mixing process between the primary and entrained flows within the steam ejector. In this study, a novel ejector model with species transport is proposed that can clearly elucidate how, when, where and to what extent the two streams mix. Systematic quantitative analysis toward the mixing of two streams

The present study examines the influence of polyolester lubricant oil (POEA-68 and POEA-170) with R-134a on the nucleate pool boiling performance for a horizontal smooth tube. The heat flux ranges from 10 kW/m2 to 90 kW/m2 and the lubricant mass fraction varied from 1% to 10% at a saturation temperature of 10 °C, 0 °C and, -6 °C, respectively. The experimental results show that the heat transfer coefficient

In this paper, an ejector-based multi-evaporator refrigeration system is proposed for the tropical region refrigerated trucks. CFD simulations are performed to study the auxiliary entrainment effect of the ejector operated in air-conditioning - freezing mode. First, the performance of the ejector with various auxiliary hole position in different chambers is investigated. Then, based on the optimal

In this study, an investigation was made into the economic effects of the integration of residential-scale energy devices. The detailed calculations were performed using an experimentally validated model of a natural gas-fueled micro-cogenerator (micro-CHP) along with data from long-term measurements of a photovoltaic (PV) system. The model of the prosumer system was enriched by integrated electrical

The organic Rankine cycle (ORC) has been proven as one of the most effective technologies for low-grade heat recovery. However, its efficiency is limited due to exergy losses caused by the large temperature difference between the heat source and working fluid in the evaporator. To enhance the ORC system efficiency, in this paper, a novel partial evaporating dual-pressure ORC (PEDORC) system is proposed

The determination of ground thermal properties is essential to design competitive commercial ground source heat pump systems. A thermal response test (TRT) carried out on site allows the determination of both the conductivity of the ground and the borehole thermal resistance by means of analytical approaches, which require several simplifying assumptions as well as TRT durations of at least fifty hours

The utilization of geothermal energy for melting snow and ice on bridge decks has been shown to be effective. However, the existing geothermal heating systems work through hydronic loops embedded inside the bridge deck and therefore are only applicable to new bridges. A new external geothermal heating design for bridge de-icing has been explored in concept and tests in the laboratory, showing great

The development of nanotechnology makes nanoparticle additives for internal combustion engines possible and the existing research results have shown that the engine performances can be improved with metal-based nanoparticles additive in the fuel. The present study makes an attempt to add aluminium oxide (AL2O3) nanoparticles (25, 100 ppm) into diesel-methanol blends, and to study the impact of the

The effect of injection pressure on impinging ignition at low temperatures is not systematic or even confusing. This work is to reveal the impinging ignition mechanism by the numerical method to further improve the success rate and thermal efficiency at cold-start conditions in a diesel engine. In which, n-dodecane was used as the diesel surrogate, and the intermediate reaction radicals, equivalence

This study presents a combined experimental and numerical investigation of the performance of a new modular sensible heat storage system with a cement based, water saturated, porous storage matrix and a helical tubular heat exchanger during cyclic storage operation. To characterize the storage system with respect to achievable storage rates and storage capacity, two sets of dedicated and highly controlled

Insights into thermal failure features under varied heating powers are significant for the safe application of lithium ion batteries. In this work, a series of experiments were conducted to investigate the thermal failure features of fully charged lithium iron phosphate battery by means of copper slug battery calorimetry. Batteries were given a total quantity of external heat (16 kJ) under various

Phase change processes in latent heat thermal energy storage (LHTES) units are relevant, due to their ability in storing surplus power generated from renewable and conventional power plants. Macroencapsulation of phase change material (PCM) is one of several approaches to increase the mean discharging and charging power of such storage units. Numerical modelling and simulation in this context is a

Oxy-fuel combustion has drawn much attention as a promising CO2 capture and storage/sequestration technology. Radiative heat transfer of oxy-fuel flames is more important than that of conventional flames owing to higher concentrations of radiating gases. The Full-Spectrum Correlated K-distribution (FSCK) methods with original correlated-K scheme (Modest and Zhang, 2002), the improved one (Cai and Modest

The effects of geometric and thermal properties of multilayer nominal three-dimensional chip on the temperature hotspots are investigated in this work. Based on heat-transfer computational fluid dynamic analysis, various effective parameters which correlate with reducing the hotspot temperature are studied. A new analytical method for the equivalent thermal conductivity of the thermal interface material

Diesel engine parameter prediction became a topic of interest in recent years, along with the development of condition-based maintenance, and is now considered a key instrument for engine diagnosis research. This contribution compares two different approaches for diesel engine performance prediction: thermodynamic modelling and artificial neural networks (ANNs). The thermodynamic modelling was developed

As an answer to the reactor accidents in Fukushima, an additional safety concept is currently under development. The aim is a retrofitting of existing and installation in new nuclear power plants. The new concept is a self-propelling supercritical CO2-operated decay heat removal system based on the Brayton cycle. To be able to prove the functionality of such a system or to investigate next-generation

Partial admission can ensure the efficient operation of the turbine unit while adjusting the aerodynamic load. It has a wide range of application prospects due to its advantages. However, the rotor blades of partial admission turbine are subjected to periodic airflow excitation, which affects the blade fatigue life to a large extent. Based on the control stage model, the optimized chamber structure

On-board modelling of gas turbine aero-engines over the life cycle is a promising solution for engine performance improvement and future aero-propulsion requirements. In this paper, an on-board modelling approach named Hybrid Wiener model (HWM) is proposed for gas turbine aero-engines using post-flight engine monitoring data, which aims at estimating the unmeasured safety-critical control parameters

Flow-induced noise and vibration problems of tube bundles in heat-exchangers exist for a long time and often cause severe destruction, performance reduction and large maintenance charge. It is essential to study the flow-induced noise in tube bundles and develop high-efficiency noise elimination measures. The theoretical analysis and numerical simulation method are coupled to compare the aerodynamic

The design of gas turbine combustors is an iterative process which is often limited by the available modelling tools. While high degrees of modelling accuracy have been achieved using high fidelity tools, these are computationally expensive and not appropriate for design space exploration. By contrast, reduced order models carry low computational expense, but cannot fully reconstruct the combustion

Nowadays, waste-to-energy systems have attracted more and more attentions. Gasification technology is one of the most important methods of waste-to-energy utilization. For further using the residual heat of the gasification system, a desiccant dehumidification unit with heat recovery using desiccant coated heat exchanger (DCHE) driven by waste heat is developed. Two DCHEs are employed to remove moisture

A parametric analysis of the thermal performance of flat polypropylene pulsating heat pipes (PHPs) is presented. In particular, the thermal performance was characterized for pulsating heat pipes with different number of turns of the serpentine channel, different orientations with respect to gravity, and containing different heat transfer fluids. The dependence of polymeric PHPs performance on design

Two important problems are often encountered in the application of middle-deep geothermal heat pump (MD-GHP) systems: (1) large deviations between the operating and design conditions and (2) the lack of a theoretical basis for parameter control during actual operations. Accurate heat transfer and energy conversion models of MD-GHP must be established to solve these problems. The novelty of this work

Solar thermal desalination is a viable approach for sustainable water production. Current thermal desalination technologies suffer from high specific energy consumption and energy mismatch. Concentrating solar collectors operate with high temperature energy and desalination systems operate with low temperature energy which leads to large exergy destruction. Herein, a thermodynamic model of an ideal

The present study investigates the reactive gas flows in T-shape microreactors by means of a 3D direct simulation Monte-Carlo method (DSMC). The reactive process is modeled by incorporating a single step irreversible exothermic reaction of gas species A and B. The energy released in each reaction is added to the system by increasing the kinetic energy of the product gas specie C. The reactive collisions

In this paper a method is introduced to determine the area primarily contributing to heat transfer of spray and jet impingement cooling below boiling point. The setup is based on temperature measurement via an infrared camera. This camera is pointed at the back of a metal plate, whereas the nozzle is spraying from the front. This technique is especially suitable for heat transfer areas with different

An aluminum vapor chamber for the thermal management of a rectangular battery cell was fabricated, and its thermal performance was thoroughly investigated according to the working fluid, cooling plate placement, and filling ratio. The heat-generation from the battery cell was simulated using a flexible surface heater with the size of 90 × 90 mm2, and the heat transfer rate was varied from 2 to 40 W

There is high risk of water inrush and ground collapse when tunneling in sandy cobble stratum in confined aquifer. Among various methods, artificial freezing method is an effective method to pre-reinforce the soft ground to prevent water inrush and ground collapse during tunneling. This paper mainly focuses on application of artificial freezing method using liquid nitrogen in sandy cobble stratum in

Ionic wind pumps have considerable potential for flow control, heat transfer, and drying applications due to their advantages of low energy consumption, compact structure, flexible design, and lack of moving parts. However, a high flow rate ionic wind pump with large cross-sectional for cooling high thermal power electronic devices requires further research. In this study, a two-stage ionic wind pump

In this study, a coupled battery model was developed by employing a novel entropic term estimation procedure to predict the thermal behavior of a Li-Ion battery for varying charge and discharge rates under different operating temperatures. In the experimental part, a battery testing system was first used to determine the fundamental thermal and electrical operational behavior of a Li-Ion battery at

Recirculating cooling water systems are used to absorb heat in the heat exchanger network, usually operating in a parallel configuration and returning water to the cooling tower with a higher temperature. This configuration receives the fresh cooling water directly without any previous reuse. While this configuration is simple to operate, it leads to inefficient use of the cooling water. On the other

A major objective in the design and operation of buildings is to maintain occupant comfort without incurring significant energy use. Particularly in narrower-plan buildings, the thermophysical properties and behaviour of their façades are often an important determinant of internal conditions. Building facades have been, and are being, developed to adapt their heat and mass transfer characteristics

The objective of this study was primarily directed to the development of experimental setups to investigate the potential of supercritical multithermal fluid (SCMTF) flooding processes. Then, the recovery mechanisms of SCMTF flooding were proposed for the first time. Finally, the impact of the injection temperature, injection pressure, injection rate, and supercritical nitrogen (scN2) and supercritical