Gábor L. Szepesi

Horizontal scraped surface heat exchanger — Experimental measurements and numerical analysis

This paper deal with the overall heat transfer process and confrontation of experimental measurements and their numerical solutions on simplified model, inside the horizontal scraped surface heat exchanger. The experimental measurements were done on two horizontal scraped surface heat exchangers connected in series. As a product was thermally treated water, heated by vapor in the first stage and cooled by cold water in the second stage. Applied mass flow of the product: m=250, 500, 750, 1000 kgh−1 and rotary velocity of the shaft, scraper blades: rpm=20, 30, (45), 60, 90 min−1. For numerical analyses the simplified model was used, with taking only the area between the heat transfer tube, and the shaft with an aim to compare the result to experimental measurements and validate the obtained overall heat exchange, as justify the simplification. As a results from experimental measurements were obtained the correlations for Nusselt number in a form of Nu=f(Re,Pr,ηf/ηw). Based on the confrontation of results, i...

Review Article: Effect of Ethanol-Gasoline Fuel Blends on the Exhaust Emissions and Characteristics of SI Engines

The stricter worldwide emission legislation and growing demands for lower fuel consumption and anthropogenic CO, NOx and HC emissions require significant efforts to improve combustion efficiency of SI engines while satisfying the emission quality demands. In this review, different volume % of ethanol fuel combined with gasoline provide particularly promising and at the same time, a challenging approach. Ethanol is widely used as an alternative fuel or an effective additive of gasoline due to the advantage of its high-octane number and it self-sustaining concept, which can be supplied regardless of the fossil fuel for the contribution of its faster flame speed, leading to enhanced combustion initiation and stability and improved engine efficiency. As a result, numerous studies have been carried out to study its effects on engine performance and emission.

Numerical and Experimental Study of Finned Tube Heat Transfer Characteristics

The automotive radiators are one of the most important ancillary equipment of the vehicle engines. This appliance cooling the engines with circulation of cooling fluid between the engine block and the radiator. The mass of the ancillary equipment is an important viewpoint, so every saved kilogram means performance growth and can help to achieve a cost-effective operation. Even though under-sizing of this thermal energy system cause life span decreasing.

Investigation of Pressure Rise in Automotive Airbags

Safety is a widely spread topic in engineering, from specific producing processes to everyday life. Innovation of passenger cars belongs to the frontline of industrial sector. Higher and higher performance motors, more streamlined vehicle dynamics, more reliable autonomous vehicles, and minor noise and vibration are the most expected developments what customers prefer. However, it is not allowed to forget automotive safety, which effectiveness prevents fatalities to drivers and passengers.

Optimal Design of Double-Pipe Heat Exchangers

Heat exchangers are used in industrial and household processes to recover heat between two process fluids. This paper shows numerical investigations on heat transfer in a double pipe heat exchanger. The working fluids are water, and the inner and outer tube was made from carbon steel. There are several constructions which able to transfer the requested heat, but there is only one geometry which has the lowest cost. This cost comes from the material cost, the fabrication cost and the operation cost. These costs depend on the material types and different geometric sizes, for example inner pipe diameter, outer pipe diameter, length of the tube. The performance of the heat exchanger and the pressure drop are in a close interaction with the geometry. Optimum sizes can be calculated from the initial conditions (when one of the process fluid inlet and outlet temperature and the flow rate is specified). The correlations to the Nusselt number and the friction data come from experimental studies.

Combustion Optimization in Spark Ignition Engines

The blending technique used in internal combustion engines can reduce emission of toxic exhaust components and noises, enhance overall energy efficiency and reduce fuel costs. The aim of the study was to compare the effects of dual alcohols (methanol and ethanol) blended in gasoline fuel (GF) against performance, combustion and emission characteristics. Problems arise in the fuel delivery system when using the highly volatile methanol gasoline blends. This problem is reduced by using special fuel manifold. However, the satisfactory engine performance of the dual alcohol–gasoline blends need to be proved. The test fuels were GF, blend M35g65 (35 % methanol, and 65% GF by volume), blend E40g60 (40% ethanol, and 6o% GF by volume). The blend M35g65 was selected to match the vapor pressure (VP) of GF. The test fuels were a lean mixture with excess-air ratio of λ=1.1. The reaction parameters are taken from literatures and fitting calculations. Mathematical model and Computer software AVL program were conducted on a naturally-aspirated, spark ignition engine. The results show that indicate thermal efficiency (ITE) improved whereas the exhaust gas temperature (EGT) of the blends reduced, which is a benefit that reduces compression work. The regulated emissions were also reported. The blend E40g60 was recommended in preference to use because the former had shortened combustion duration, high energy content and its VP was selectively matched to that of GFs.

Theoretical and Parametric Investigation of an Automobile Radiator

Automotive radiator is one of the most important devices of the engine cooling system. The function of this equipment is to remove heat from the engine and to keep the engine operating at the most efficient temperature. Nowadays, in the automotive industry, one of the most important project is decreasing the mass. This chapter focuses on calculation and optimization of finned-tube heat exchanger using several methods.