The Miller cycle, using an early inlet valve closing, can significantly improve the overall efficiency of a spark ignition engine during partial load operations. The shorter valve intake event minimizes the need for throttling the air and so reduces the pumping losses. This method is known as “dethrottling”. Indeed, the use of a variable valve lift system makes it possible to combine two different

This work develops a new and effective method to predict the 2-D cooling effectiveness distribution. The assumption in the existing 1-D method is abandoned and replaced by a scalar diffusion equation to model the lateral spreading of the coolant. The proposed model can be used for predicting 2-D multi-row cooling performance and is validated over four arrangements of double-row cooling holes against

Regenerative cooling is critical for hypersonic propulsion systems, wherein the flow and heat transfer characteristics of the hydrocarbon fuel in the cooling channel are crucial. The most commonly used existing evaluation models for flow and heat transfer characteristics use one-step overall reaction endothermic pyrolysis; however, they are limited to mildly cracked hydrocarbon fuel working conditions

In order to develop a heat transfer enhancement technique for molten salt heat exchanger, Fluent simulation is carried out to investigate the molten salt flow and heat transfer performances in annular channels with wire coil. Two experimental set-ups were built to measure the temperature distribution of the test section, and the maximum relative deviation between the simulated temperature and experimental

This research was conducted to better understand the mechanisms of heat and moisture transfer of walnuts during drying in a fixed-bed column dryer with heated air, and to develop a mathematical model to simulate this process. Drying experiments were performed under constant temperature and step-down temperature conditions (43, 55, 65 and 75 °C) with fixed air velocity of 0.7 m/s. The nonequilibrium

Previously, the conventional fin-and-tube heat exchanger is usually chosen as the evaporator in the air source heat pump. Recently, with the higher heat transfer efficiency, the microchannel heat exchanger is increasingly recognized. Nevertheless, information available in the contrastive analysis of the two heat exchanger types is scarce. Therefore, the effect of the mentioned evaporator type on the

The boiling bundle effect was investigated on a column of reentrant cavity tubes to reveal the heat transfer coefficient (HTC) variation for a tube which is affected by other tubes. All experimental data were obtained on the specific tube, which is the distinct difference between the adopted homologous method and the routine method. Two columns of eight horizontal tubes were submerged in R134a liquid

The aerothermal performance of a novel compound heat transfer enhancement method is assessed by measuring the full-field endwall Nusselt number map and Fanning friction factors of a rotating two-pass furrowed channel roughened by angled ribs. The tested Reynolds numbers, rotation numbers, and buoyancy numbers lie in the respective ranges of 5,000–15,000, 0–0.4, and 0–0.183. Under the combined effects

High temperature and humidity conditions in enclosed cabins pose a threat to the safety of staff and equipment, and will result in intensive energy consumption by conventional air conditioning dehumidification systems. Therefore, an improved dehumidification system integrated with precooling and recirculated regenerative rotary desiccant wheel was proposed. The effects of the process air parameters

Landfill gas waste heat power generation is an effective way to promote the efficiency and economics of power plants. However, the operating performance of the power generation system needs to be improved further. In this paper, a systematic optimization research on the off-design characteristics of the partial heating supercritical carbon dioxide power system for exhaust heat utilization from gas

An in-depth understanding of the convective drying mechanism is significant for improving industrial production efficiency and reducing available energy consumption. In this research, a conjugate numerical model appropriate for representing the convective drying is developed and incorporated into the computational fluid dynamics framework, which adopts a non-equilibrium approach to depict the thermal

In this paper, a theoretical investigation of a solar-powered adsorption-based trigeneration system under the climate conditions of Alexandria, Egypt has been performed. The system is intended to provide the required cooling, electricity and domestic hot water (DHW) loads for a building in Alexandria throughout the year. The system comprises commercial Photovoltaic/Thermal (PVT) and Evacuated tube

The visualization method is used to study the heat transfer performance of ultra-thin flat heat pipe (UTFHP) with a vapor chamber thickness of only 0.8 mm under different liquid filling rates, and observe the change of vapor–liquid interface in mesh wick and the flow characteristics of working fluid in vapor chamber, which has important reference value and guiding significance for determining the optimal

Air and hydrogen feeding control is a hot topic for the operation of proton exchange membrane (PEM) fuel cell system. However, there is little consideration for the cooperative control of the oxygen excess ratio, hydrogen excess ratio and the pressure balance between anode and cathode. This paper proposed an adaptive super-twisting (ASTW) based sliding mode nonlinear control to regulate air, hydrogen

The output and adsorption characteristics of solid adsorbents limit their application in a desiccant wheel system. Therefore, this paper proposed a macroscopic green synthesis method for aluminum fumarate metal organic framework (approximately 400 g can be synthesized in a single time). By combining with other materials, the dehumidification performance of aluminum fumarate had been greatly improved

Uncertainties may skew the understanding of experiments or numerical simulations results. The impact of the flow parameters uncertainties of measurement on wall heat flux is investigated in a non-isothermal turbulent channel flow. A heat transfer correlation dedicated to gas-pressurized solar receivers of concentrated solar tower power is used. Both symmetric and asymmetric heating conditions are tested

This experimental research was performed for the measurement-based detection and numerical simulation of a biological multiphase flow in a fermentation tank. The difficulties of an investigation are the many complex interactions between the different three phases (yeast as solid, carbon dioxide as gas, wort as liquid). One of the main difficulties is, that the natural convection processes are superimposed

The closed Brayton cycle is promising as a power generation system owing to its output flexibility and compactness. In this study, a small closed Brayton cycle device was developed and its transient characteristics were studied experimentally and numerically. The start-up procedure for a closed Brayton cycle with considerable thermal inertia and heat dissipation was investigated. First, a modelling

The air-side heat transfer performance of herringbone wavy fin-tube heat exchangers can be improved by optimizing fin geometries and introducing perforations to the wavy fin. Based on a typical herringbone wavy fin-tube heat exchanger used in the outdoor unit of an air conditioner with collar outside diameter of 7.3 mm, transverse tube pitch of 22 mm, and longitudinal tube pitch of 19.05 mm, the effects

This study investigates the cold thermal energy storage (CTES) using a helical coil heat exchanger modified with bubble injection. A helical coil heat exchanger is immersed inside a cylindrical water storage tank, where the helical coil is the evaporator of a vapor compression refrigeration cycle (VCRC) and provides the designed cooling. Experiments were performed to examine the effect of bubble injection

We present the performance of an active magnetic regenerator prototype with a multi-bed concept and parallel flow circuit. The prototype applies a two-pole permanent magnet (maximum magnetic flux density of 1.44 T) that rotates over 13 tapered regenerator beds mounted on a laminated iron yoke ring. Each bed is filled with about 260 g of spherical particles, distributed in layers of ten alloys of La(Fe

In order to enhance the Departure from Nucleate Boiling (DNB) type critical heat flux (CHF) of the divertor in International Thermonuclear Experimental Reactor (ITER), the novel compound heat transfer tube (CHTT) was proposed as a compound CHF enhancement technique by inserting a twisted tape into an internal thread tube (ITT). Firstly, the experiments were investigated for subcooled water flow boiling

The paper discusses an approach to the design of the forced air-cooling heat sink for power electronic application to uniformly distribute the temperature of the semiconductor modules fixed on the top of the heat sink. The proposed approach suggests a minor modification of a conventional fin-based heat sink commonly manufactured for cooling of power electronic modules. Following the proposed modification

In this paper, we present a detailed comparison study on the prediction accuracy by two different and simplified battery models, namely Lumped and Li-ion (1D electrochemical) model, for a prismatic 20Ah LiFePO4 battery sandwiched between minichannel cold-plates with distributed flow. A two-way coupling between the battery model (Li-ion/Lumped) and 3D conjugate heat transfer model is considered for

The divertor is one of the core components in the Tokamak magnetic confinement nuclear fusion device, which is responsible for eliminating high-flux energy flow and particle flow. The divertor in China Fusion Engineering Test Reactor (CFETR) is designed to withstand a steady-state thermal load of 10 MW/m2 and a transient thermal load up to 20 MW/m2. The water-cooled scheme is a promising candidate

This paper proposes a hybrid cooling system which combines a commercial bottom liquid cooling system and a novel dielectric flexible composite phase change material (FCPCM). This hybrid cooling system ensures the safety and high performance of Lithium-ion battery under abuse conditions, such as a high-rate discharge of 6C and a high ambient temperature of 40 ℃. The cooling performances of different

A solid copper pad is integrated into the heating side of a wickless copper thermal ground plane (TGP) with deionized water as the working fluid. Experimental TGP performance tests, along with pool boiling experiments and conduction thermal numerical simulations, are used to quantify the effect of the copper pad thickness on the overall thermal performance of the TGP. Even though adding the copper

The falling film flow has attracted much attention recently due to its advantages of low temperature difference, low flow rate, high heat transfer coefficient and high heat flux density. In this paper, a series of experiments were carried out to investigate the falling film flow and heat transfer characteristics outside the vertical tube based on the established experimental system. Flow patterns,

In this study, the Eulerian-Lagrangian method is employed to inspect the impact of nanoparticle migration on the hydrothermal and entropy generation features of Fe3O4–water nanofluid in a ribbed-blocked microchannel with two different arrangements. The results are compared with those of the plain microchannel at different volumes of flow rate and nanoparticle concentration. It was found that the nanoparticle

Low-temperature preheating to achieve effective thermal management for lithium-ion batteries is a crucial enabler for the efficient and safe operation of electric vehicles in cold conditions. Effective heating is yet challenging due to its implementation complexity and a tricky balance of the heating performance. Here, we develop a lightweight compound self-heating system involving two external light

This paper is presenting the numerical investigation of the frosting behavior of a heat pump evaporator in its full complexity, imitating the real-life operation of the experimental setup described in Part A of this publication. The backbone of this work represents the simulation framework for the selected algebraic frost growth model, with the novelty focused on its implementation into a 3D unstructured

Laboratory rodent room usually adopts full fresh air system with large ventilation rates and causes energy waste for heat-cold offset process. Liquid desiccant system is identified as an energy saving approach in humidity control field. This paper presents the ammonia absorption performance of a liquid desiccant dehumidification system applied in laboratory rodent room while considering air dehumidification

Considering that square ducts are widely utilized for HVAC system performance testing, air mixing devices designed for such ducts were experimentally investigated. The results of these studies can also inform field application of mixers, such as in airside economizer applications of rooftop air conditioning equipment. Three types of air mixing devices were considered; one was a louvered-type mixer

Cold Thermal Energy Storage (CTES) technology can be introduced to refrigeration systems for air conditioning and process cooling to reduce the peak power consumption by decoupling the supply and demand of refrigeration. In these systems, the refrigeration demand can vary significantly over a day, resulting in a challenging peak and valley load pattern on the electrical grid. This paper presents the

High concentrator photovoltaic is expected to play an increasingly important role in electrical energy production. Controlling multijunction solar cell temperature within the recommended conditions is a key challenge that limits the functionality of this growing technology making the identification of an efficient cooling method an essential requirement. Hence, in this research, new heat sink configurations

Seasonal thermal energy storage is an effective measure to enable a low carbon future through the integration of renewables into the energy system. Borehole thermal energy storage (BTES) provides a solution for long-term thermal energy storage and its operational optimization is crucial for fully exploiting its potential. This paper presents a novel linearized control-oriented model of a BTES, describing

The longitudinal flow heat exchanger possesses lots of merits but it exhibits poor heat transfer coefficient at low Re condition, which makes it difficult to be applied in the high viscosity fluid area. In this paper, a heat transfer augment solution for lubricating oil flowing on shell side of a novel longitudinal flow twisted trifoliate tube oil cooler was proposed. Experiments were conducted to

This paper presents an experimental investigation of the influence of multiple parameters on the thermal performance of variable conductance heat pipes (VCHPs) according to theoretical design and analysis. The operating characteristics of four VCHPs, such as the steady-state temperature, thermal resistance, and degree of self-control, were systematically analysed and compared. The design principles

Waste heat elimination via integration techniques has been recognized as an effective solution for the performance enhancement of renewable energy-based power plants. In this paper, a new plant, based on an external reformer molten carbonate fuel cell, is proposed and analyzed. The system consuming the biogas fuel produced by a digester plant. A gas turbine and a supercritical CO2 cycle are used as

The moisture from residual droplets during construction and infiltration of wet air during operation can cause metal corrosion of main cables on suspension bridges. Main cable dehumidification, emerged as a prospective corrosion protection approach, which provides an internal environment of relative humidity below 60%, would significantly mitigate the corrosion. This paper presents a state-of-the-art

In this paper, a novel hybrid-connected two-stage liquid dehumidification fresh air (HTLDFA) system by combining CaCl2 with LiCl aqueous solutions is proposed, in which the ambient air is adopted directly as the regeneration air of CaCl2 solution and the air pre-dehumidified by part of the strong CaCl2 is used for regenerating the LiCl solution. In this way, regeneration air of lower humidity for LiCl

Internal Combustion Engine (ICE) cooling system is receiving a new technological interest for the influence it has on primary harmful and CO2 emissions reduction. Improvements on pump efficiency are requested to reduce its required energy during real on-the-road operation. Present technology always considers centrifugal pumps whose efficiency is highly dependent on rotational speed: consequently, pumps

Past researches have shown that CO2/HFC mixtures and microchannel heat exchanger could benefit solving the problems of high operating pressure and relatively low cycle efficiency. In this paper, the supercritical heat transfer characteristics of R41, CO2/R41 (20.5/79.5) and CO2/R41 (51.4/48.6) in square porous flat tube microchannel with the hydraulic diameter of 0.715 mm were experimentally studied

The key to the design of dusty flue gas heat exchangers is to enhance heat transfer and solve the fouling problem. In this paper, a honeycomb 4H-type finned tube heat exchanger (FTHE) was proposed. A three-dimensional numerical investigation was conducted on heat transfer and flow friction characteristics of honeycomb 4H-type FTHEs. Firstly, the flow field and temperature of H-type FTHEs with inline

In this study, a new heat dissipation device with a composite heat sink of a loop heat pipe (LHP) system was evaluated for efficient cooling of electronic components. To improve the heat dissipation ability of the high heat flux chip and its local hot spot area, LHP, which had a gas-liquid phase change as the main mechanism of heat dissipation, was selected to remove heat. The experimental results

Power electric devices, such as line inductors or transformers, are limited by current, voltage, and operating temperature. Current is the main culprit behind the heating of all electric devices. Excess heating leads to faster degradation of the insulation and lowers the breakdown voltage. These factors determine the lifetime and reliability of these devices, which can be extended by lowering the operating

Stress control of boilers is a major concern in the aged power plants. The studied forced circulation boiler suffers from a malfunction of the combustion control system. In order to reduce cyclic stress on boiler equipment and prevent undesirable shutdowns of power unit during fuel shortage events, an operating instruction is proposed. In order to predict dynamic behavior of the boiler, a nonlinear

The cooling performance of indirect evaporative cooler (IEC) largely depends on the wettability of wet channels. Therefore, plant fiber-polymer composite was used as a novel evaporative material to enhance the wettability in IECs in this study. The plant fiber layer facing to the wet channel is hydrophilic, which can disperse water effectively by capillary action, while the opposite non-permeable polymer

The paper presents the results of investigation of thermal characteristics of a flat evaporator 10 mm thick with an active zone of 27 cm2 that is part of a copper–water loop heat pipe (LHP) intended for cooling systems of high-power electronic components. The investigation of the device was conducted in a horizontal position with heat sources having thermocontact surfaces of 9 cm2, 16 cm2 and 25 cm2

In this work, the dynamic heat rejection of a VO2-based nanophotonic variable-emittance coating is demonstrated in a cryothermal vacuum experiment that simulates a cold space environment. The fabricated coating displays a significant augmentation in radiated heat flux, from 136 W/m2 at the onset of the VO2 insulator-to-metal phase transition to 444 W/m2 at the end, which is in excellent agreement with

In this paper, several alternative models were developed with multiple linear regression and machine learning algorithms to determine the output states of silica gel desiccant wheels for balanced flow. The decision tree method was used for this purpose for the first time in open literature. All the models developed include six input parameters and a wider range than those available in the literature

Clothes dryers play an important role in modern daily life which consumes a lot of residential electricity. The closed-loop heat pump clothes dryer is a typical energy-saving application in heat pump drying. To predict and analyze both electricity consumption and drying time, a quasi-steady-state model of the closed-loop heat pump dryer was developed, which consists of a dynamic fabric drying model