Mahmoud Khaled

A new method for simultaneous measurement of convective and radiative heat flux in car underhood applications

A new experimental technique is presented that allows simultaneous measurement of convective and radiative heat flux in the underhood. The goal is to devise an easily implemented and accurate experimental method for application in the vehicle underhood compartment. The new method is based on a technique for heat-flux measurement developed by the authors (Heat flow (flux) sensors for measurement of convection, conduction and radiation heat flow 27036-2,

Short review on heat recovery from exhaust gas

The increasing growth of energy demand leads to issues associated with energy demand reduction and propose new energy efficient solutions. Heat recovery consists the most promising solution especially in regions where renewable energy resources are not available. That is why the domain of heat recovery has shown a tremendous improvement during the recent years. On the other hand, few works have been dedicated to heat recovery from exhaust gas. This paper presents a review on heat recovery from exhaust gas. The authors propose to classify exhaust gas heat recovery systems within three different classifications that are exhaust gas temperature, utilized equipment and recovery purposes.

Short review on solar energy systems

Solar energy can be utilized mainly in heat generation and electricity production. International energy agency (IEA) shows, in a comparative study on the world energy consumption that in 2050 solar arrays installation will provide about 45% of world energy demand. Solar energy is one of the most important renewable energy source which plays a great role in providing energy solutions. As known there is wide variety of types of collectors and applications of solar energy. This paper aimed to make a short review on solar energy systems, according to types of collectors and applications used.

Design and analysis of an HVAC-based heat recovery system

In this paper, the design of a heat recovery system is presented and analyzed. It allows recovering the heat waste from Heating, Ventilating, and Air Conditioning (HVAC) systems to obtain hot water. A code is developed for this purpose, which allows simulating the heat transfer in the system. The outlet temperature is studied in terms of the water flow rate and the amount of ton refrigerant in the system. It is shown that the water can be heated up to 347 K with a HVAC system of 9 tons of refrigerant (108 000 Btu/hr).

Parametric Analysis of Heat Exchanger Thermal Performance in Complex Geometries—Effect of Air Velocity and Water Flow Distributions

The thermal performance of automotive heat exchangers is greatly affected by the relationship that binds the nonuniformities in flow velocity and the distribution of upstream temperatures. Consequently, an in-house two-dimensional code is established to evaluate the thermal performance based on known parameters, namely, distribution of upstream velocity of an air–liquid heat exchanger, the flow rate of heat exchanger liquid, and the inlet air and liquid temperatures. A parametric research study is then performed to confirm the relation between the thermal performance of the heat exchanger and these different parameters. It was observed that nonuniformities in air velocity and water flow distributions decrease the thermal performance of a heat exchanger by up to 33 and 42%, respectively.

Heating water using the recovered chimney waste heat - Prototype and experimental analysis

This work discusses a waste heat recovery system applied to chimneys allowing to heat water in residential buildings. A prototype illustrating the idea is implemented and tested. Different waste heat scenarios by varying the quantity of burned firewood (heat input) are experimented. Temperature measurements are performed at different parts of the heat recovery system. Gas flow rates of the Exhaust pipes of the system are also measured. Using this system, measurements showed that a tank of 95 L of water can be heated up to 78 °C within one hour. Obtained results show that the convection and radiation exchanges at the bottom surface of the tank have a considerable impact on the total heat transfer rate of the water (up to 70%) used in the prototype under test.

Study of the Thermal Behavior of Multi Tube Tank in Heat Recovery from Chimney—Analysis and Optimization

ABSTRACT This work discusses the utilization of multi tube tank heat exchanger for waste heat recovery. The thermal behavior of the system is studied in order to understand the contribution of the different heat transfer modes governing the system. As application, heating water in residential application from chimney heat recovery is considered. A prototype illustrating the suggested system is implemented and tested. Different waste heat scenarios by varying the quantity of burned firewood (heat input) are experimented. The temperature at different parts of the system and the gas flow rates of the exhaust pipes are measured. Measurements showed that the temperature of 95 L tank of water can be increased by 68°C within one hour. Obtained results show that the convection and radiation exchanges at the bottom surface of the tank have a considerable impact on the total heat transfer rate of the water (as high as 70%). Moreover, the proposed system allows saving 9.8 L of gasoline, 10.6 L of diesel or 15 kg of wood for 12 hours of chimney operation.

Simulation of Incremental Forming Processes Using a Thermo-Mechanical Partitioned Algorithm

The aim of this paper is to study the simulation of cogging process using a thermo-mechanical partitioned algorithm. The thermal and mechanical problems are solved separately. The mechanical problem is based on the balance equation whereas the thermal problem is based on the heat equation. The two physics are coupled trough the mechanical parameters that depends on the thermal problem and vice versa. The results obtained using the software Forge3 show that the mechanical deformation is high inside the zone of deformation and negligible outside whereas the temperature is high overall the mesh with a gradient at the zone of contact between the dies and the work piece.

Heating residential water using parabolic trough concentrators: theoretical calculations and analysis

The present work concerns theoretical and case studies related to a new design of residential water heating using parabolic trough. To proceed, the thermal modelling of parabolic trough concentration and flat plate heat collection is drawn. Then, the case of Beirut city is considered to compare the performance of three different configurations of heating water: flat plate, parabolic trough and parabolic trough with tracking. It was shown that the enhancement of water heating using parabolic trough with respect to flat plate collector depends on the criterion of comparison. Particularly for the same volume occupied on the roof, the use of parabolic trough has shown to decrease the time of heating water to 70°C by 22.4% (a decrease from 52.2 h to 40.5 h) without tracking and 33% (a decrease from 52.2 h to 35 h) with tracking.

Application of multi-grid method on the simulation of incremental forging processes

Numerical simulation becomes essential in manufacturing large part by incremental forging processes. It is a splendid tool allowing to show physical phenomena however behind the scenes, an expensive bill should be paid, that is the computational time. That is why many techniques are developed to decrease the computational time of numerical simulation. Multi-Grid method is a numerical procedure that permits to reduce computational time of numerical calculation by performing the resolution of the system of equations on several mesh of decreasing size which allows to smooth faster the low frequency of the solution as well as its high frequency. In this paper a Multi-Grid method is applied to cogging process in the software Forge 3. The study is carried out using increasing number of degrees of freedom. The results shows that calculation time is divide by two for a mesh of 39,000 nodes. The method is promising especially if coupled with Multi-Mesh method.