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Several techniques for cooling mass concrete structures were developed in order to increase structural integrity and reduce the influence of cement hydration, which sometimes causes cracking in concrete structures, negatively affecting their durability. This research focuses on cooling system design, initial investment, and the influence of different refrigerants on cooling system performance aims in producing higher quality massive concrete. Cooling aggregates in massive concrete structures such as desert dams can be performed by employing cooled air from an air conditioning duct system or chilled water. The experimental study illustrates the relationship between the coefficient of performance COP, the evaporator temperature, cooling capacity, and refrigerant mass flow rate as a function of the evaporator temperature, cooling capacity, and refrigerant mass flow rate. The findings of the experiments were utilized to verify a numerical model developed utilizing engineering equation solver (EES) software. The performance of the vapor compression of the cooling systems was compared using alternative refrigerants, including R22, R32, and R410a at different operating conditions. This study revealed that R22 refrigerant has a higher coefficient of performance than R32 and R410A, while R32 has the highest cooling capacity among other refrigerants.

This paper presents the possibility of using the numerical methods to analyze the work of hydraulic systems on the example of a cooling system of a power boiler auxiliary devices. The variety of conditions at which hydraulic system that operated in specific engineering subsystems requires an individualized approach to the model solutions that have been developed for these systems modernizing. A mathematical model of a series-parallel propagation for the cooling water was derived and iterative methods were used to solve the system of nonlinear equations. The results of numerical calculations made it possible to analyze different variants of a modernization of the studied system and to indicate its critical elements. An economic analysis of different options allows an investor to choose an optimal variant of a reconstruction of the installation.

Magnetic refrigeration is a fascinating superior choice technology as compared with traditional refrigeration that relies on a unique property of particular materials, known as the magnetocaloric effect (MCE). This paper provides a thorough understanding of different magnetic refrigeration technologies using a variety of models to evaluate the coefficient of performance (COP) and specific cooling capacity outputs. Accordingly, magnetic refrigeration models are divided into four categories: rotating, reciprocating, C-shaped magnetic refrigeration, and active magnetic regenerator. The working principles of these models were described, and their outputs were extracted and compared. Furthermore, the influence of the magnetocaloric effect, the magnetization area, and the thermodynamic processes and cycles on the efficiency of magnetic refrigeration was investigated and discussed to achieve a maximum cooling capacity. The classes of magnetocaloric magnetic materials were summarized from previous studies and their potential magnetic characteristics are emphasized. The essential characteristics of magnetic refrigeration systems are highlighted to determine the significant advantages, difficulties, drawbacks, and feasibility analyses of these systems. Moreover, a cost analysis was provided in order to judge the feasibility of these systems for commercial use.

This study presents a comparative analysis of performance, exhaust and noise emissions for a one-cylinder, four-stroke, spark-ignition engine powered by gasoline fuels of two different grades of research octane numbers (RONs), namely octane 90, and octane 95. During the experimental works, each fuel test was performed by varying the engine speed within the range from 1000 to 3600 rpm. The SI engine was connected to eddy current dynamometer with electronic control unit (ECU), an exhaust gas analyzer and the sound level meter (SLM) to determine engine performance, exhaust emissions, and measuring the sound pressure level (SPL) in decibels (dBA) and one octave frequency bands in the audible human range at different engine speeds, respectively. The experimental results showed that the using gasoline with octane grades higher than the requirement of an engine will decrease the engine performance. On average, the brake power and thermal efficiency for the SI engine fuelled with octane 90 is higher than that of gasoline octane 95 by 6% and 11% respectively, and improvement of BSFC by 14%, which is mainly due to higher heating value. Even though, the volumetric efficiency of octane 95 is more 5% than octane 90 due to higher latent heat and heat capacity. In general, the exhaust emission profiles for NOx and CO of the engine improved for octane 95 by 11% and 17% respectively. On the other side, the HC and CO2 emissions concentration of gasoline octane 90 is lower than that of gasoline octane 95 by 18% and 12% respectively. Finally, the noise levels showed a trend of the increase of disturbing for higher octane number and the increase of divergence between the two values of SPL at higher speed for both fuels.

This manuscript analyzes the sub-systems of evaporative cooler (EC) combined with desiccant dehumidification and regeneration for automotive air conditioning purpose. The thermodynamic and psychometric analysis was conducted to design all evaporative cooling system components in terms of desiccant selection, regeneration process, compact heat exchanger and evaporative cooler. Moreover, the effect of the desiccant, heat exchanger and evaporative performances on the mass flow rate and water sprayed required for evaporative cooling system was investigated. The results show that the theoretical evaporative cooling design will achieve two main objectives: lower fuel consumption and less environmental pollutants. However, it has the two drawbacks in terms of increased weight and reduces the coefficient of performance (COP). The main remark is that evaporating cooling system is more efficient than the conventional air conditioning when the gasoline price is more than 0.34 $/liter.

The energy demand for cooling and air conditioning systems is increasing worldwide, especially in regions with high solar radiation intensity. One of the reasons for this is the increase of comfort demands worldwide. The most cooling and air conditioning systems are the conventional electrically driven one type such as compression refrigeration machines and air conditioning systems. Through the huge electricity consumption for cooling and air conditioning, the environmental problems get bigger and bigger, because of carbon dioxide (CO2) and other pollutant emissions. One of the possibilities to reduce the primary energy consumption is through the use of solar energy for driving the thermal driven absorption or adsorption refrigeration systems, or desiccant cooling. Another possibility is using solar energy to produce electrical energy and this can be used to drive the conventional refrigeration systems. Many research and developmental efforts in the last years have been done to enforce the spreading of solar-driven cooling systems. This paper will illustrate the state of the art about the energy consumption for cooling and air conditioning systems, available solar-driven cooling systems and the potential of the utilization of such systems in comparison to the conventional ones. Moreover, this paper highlights some different methods of optimization, which used to maximize the performance and minimize the cost.

Performance assessment of a two-bed silica gel-water adsorption refrigeration system driven by solar thermal energy is carried out under a climatic condition typical of Perth, Australia. A Fourier series is used to simulate solar radiation based on the actual data obtained from Meteonorm software, version 7.0 for Perth, Australia. Two economic methodologies, Payback Period and Life-Cycle Saving are used to evaluate the system economics and optimize the need for solar collector areas. The analysis showed that the order of Fourier series did not have a significant impact on the simulation radiation data and a three-order Fourier series was good enough to approximate the actual solar radiation. For a typical summer day, the average cooling capacity of the chiller at peak hour (13:00) is around 11 kW while the cyclic chiller system coefficient of performance (COP) and solar system COP are around 0.5 and 0.3, respectively. The economic analysis showed that the payback period for the solar adsorption system studied was about 11 years and the optimal solar collector area was around 38 m2 if a compound parabolic collector (CPC) panel was used. The study indicated that the utilization of the solar-driven adsorption cooling is economically and technically viable for weather conditions like those in Perth, Australia.

Radiative properties of transparent insulations made of a layer of parallel, small-diameter, thin-walled, visible light transparent pipes placed perpendicularly to the surface of a flat solar absorber are investigated theoretically. A formula for the radiation heat losses through the insulation is derived based on two main assumptions: the system is in steady-state and the fourth power of the temperature along each pipe is linear. Arguments in favor of the assumptions are given. The formula, combined with standard formulas for the conductive heat flux, enables prediction that a 10 cm thick transparent insulation under insolation of 1000 W/m2, at ambient temperature 20 °C, could theoretically raise the absorber temperature to 429 °C and produce 410 W mechanical power under the ideal Carnot cycle. In order to reach that high energy conversion efficiency, the insulation pipes should have diameter less than 0.5 mm and walls about 5 μm thick, which may be technologically challenging.

This manuscript investigates the effect of emulsified diesel fuel on the engine performance and on the main pollutant emissions for a water-cooled, four stroke, four cylinders, and direct injection diesel engine. Emulsified diesel fuels with water content of range 0–30% by volume were used. The experiments were conducted in the speed range from 1000 to 3000 rpm. It was found that, in general, the using emulsified fuel improves the engine performance and reduces emissions. While the brake specific fuel consumption (BSFC) has a minimum value at 5% water content and 2000 rpm. The torque (T), the break mean effective pressure (BMEP) and thermal efficiency (ηth) are found to have maximum values under these conditions. The emission CO2 was found to increase with engine speed and to decrease with water content. NOx produced from emulsified fuel is significantly less than that produced from pure diesel under the same conditions. And as the percentage of water content in the emulsion increases, the emitted amount of oxygen also increases.

This manuscript investigates the analysis and modeling of vehicular thermal comfort parameters using a set of designed experiments aided by thermography measurements. The experiments are conducted using a full size climatic chamber to host the test vehicle, to accurately assess the transient and steady state temperature distributions of the test vehicle cabin. Further investigate the thermal sensation (overall and local) and the human comfort states under artificially created relative humidity scenarios. The thermal images are calibrated through a thermocouples network, while the outside temperature and relative humidity are manipulated through the climatic environmental chamber with controlled soaking periods to guarantee the steady state conditions for each test scenario. The relative humidity inside the passenger cabin is controlled using a Total Humidity Controller (THC). The simulation uses the experimentally extracted boundary conditions via a 3-D Berkeley model that is set to be fully transient to account for the interactions in the velocity and temperature fields in the passenger compartment, which included interactions from turbulent flow, thermal buoyancy and the three modes of heat transfer conduction, convection and radiation. The model investigates the human comfort by analyzing the effect of the in-cabin relative humidity from two specific perspectives; firstly its effect on the body temporal variation of temperature within the cabin. Secondly, the Local Sensation (LS) and Comfort (LC) are analyzed for the different body segments in addition to the Overall Sensation (OS) and the Overall Comfort (OC). Furthermore, the human sensation is computed using the Fanger model in terms of the Predicted Mean Value (PMV) and the Predicted Percentage Dissatisfied (PPD) indices. The experimental and simulation results show that controlling the RH levels during the heating and the cooling processes (winter and summer conditions respectively) aid the A/C system to achieve the human comfort zone faster than the case if the RH value is not controlled. Also, the measured and predicted transient temperatures are compared and found to be in good agreement.

SUMMARY Presented study discusses the development of a finite differencing (FD) thermal model for a power-split hybrid configuration employing a nickel-metal hydride battery pack. A resistance–capacitance electro-thermal model is used to couple the experimental boundary conditions (current, voltage, state of charge, and temperature) with the modeled battery resistance to capture its electro-chemical behavior and the cell exothermic reactions. Battery current, voltage, and temperature (discrete and full field) for a vehicle with a power-split hybrid configuration were collected under different standard (Federal Highway Driving Schedule and Federal Urban Dynamometer Driving Schedule (FUDS)) and artificially generated driving cycles. This manuscript analyzes the battery current and voltage in relation to vehicle speed and shows how the proposed FD model predicts the spatial and temporal temperature profiles of the power train in good agreement with the vehicle data as reported by the on-board diagnostics module. Copyright © 2011 John Wiley & Sons, Ltd.

This manuscript discusses the effect of manipulating the Relative Humidity RH of in-cabin environment on the thermal comfort and human occupants’ thermal sensation. The study uses thermodynamic and psychometric analyses, to incorporate the effect of changing RH along with the dry bulb temperature on human comfort. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect of relative humidity on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. The results show that changing the RH along with dry bulb temperature inside vehicular cabins can improve the air conditioning efficiency by reducing the heat removed while improving the Human comfort sensations as measured by the Predicted Mean Value PMV and the Predicted Percentage Dissatisfied PPD indices.

This manuscript discusses the development of a 3D thermal model for a power-split hybrid powertrain, including its battery modules and power electronics. The 3D model utilizes a finite differencing (FD) heat transfer algorithm, complemented with experimental boundary conditions. The experimental setup is configured to acquire the battery current, voltage, and its inner and surface temperatures in discrete and in full-field scans. The power-split hybrid configuration is tested using a standard and artificial driving cycles. A battery resistance model is then used to couple the experimental boundary conditions with the finite differencing code, which employed a cell-based internal heat generation model to describe the pack chemical reaction mechanism. This study presents a complete analysis based on battery current and voltage in relation to vehicle speed. The proposed model also predicts the powertrain spatial and temporal temperature profiles in agreement with the vehicle actual conditions as indicated by the On-Board Diagnosis (OBD) module.

This manuscript provides a comprehensive review of the different models developed to predict vehicular cabins thermal comfort, in addition to the different experimental techniques used. The review classifies the in-cabin modeling into; human physiological and psychological perspectives in addition to the compartment zone and the human thermal manikin modeling. While the experimental approaches are mainly; the subjective observers, the thermal manikins, and the Infrared Thermography. Additionally the manuscript discusses and analyses each of the thermal indices that are typically used in assessing the in-cabin conditions such as the Predicted Mean Value PMV index and the Predicted Percentage Dissatisfied PPD. The text also highlights the main attributes of vehicular thermal comfort, in terms of its fast transient behavior, the in-homogeneity in the thermal fields associated with the high localized air velocity, solar loads and flux, in addition to the inherent variations related to the trip durations.

Emulsions of diesel and water are often promoted as being able to overcome the difficulty of simultaneously reducing emissions of both oxidises of nitrogen (NO x ) and particulate matter from diesel engines. In this work, the performance of an engine together with its effect on environment were tested when engine was powered by both pure diesel and emulsified fuel with various quantities of water content in the diesel fuel. The amount of water quantities added ranged between 5% and 30% by volume. The engine speed during the experimental work was within the range from 1000 to 3000 rpm. While producing similar or greater thermal efficiency and improved NO x emission outcomes use of the emulsion also results in an increase in brake specific fuel consumption. It was also found that, at high amount of water addition, the nitrogen oxide decreases. Also, in general, the diesel emulsion fuel emitted an amount of CO 2 higher than that of pure diesel.