Ibrahim Kilicaslan

Enhancement of heat transfer in compact heat exchanger by different type of rib with holographic interferometry

Abstract An experimental study was carried out to investigate enhancement of heat transfer in compact heat exchanger by keeping pressure drop constant in a given range. Two different test matrices, cylindrical and triangular, used to find the optimum ribs were compared with a smooth channel. The investigation was performed with both laminar and turbulent forced flow for Reynolds numbers from 250 to 7000. The geometric parameters, in order to satisfied manufacturer demands, were fixed at p / e =6.67 and the wall temperature was held constant at 50°C. The technique of holographic interferometry was used to determine the temperature distribution in the test duct. Velocity distribution was measured using laser doppler anemometer techniques. For comparison the technique of global measurement was also used. The results revealed that cylindrical ribs are optimum heat transfer for conversion of pressure drop. An 8% experimental error was found in global measurement compared to holographic interferometry.

Numerical Evaluation by Models of Load and Spark Timing Effects on the In-Cylinder Heat Transfer of a SI Engine

The aim of this study is to examine numerically the effects of spark timing and load parameters on the in-cylinder heat transfer of a SI engine by using experimental engine test data. For the investigation, a four-stroke, air-cooled, single-cylinder SI engine was tested at different spark timings and loads at a single engine speed of 2000 rpm. Woschni, Hohenberg, and Han models were employed to estimate the in-cylinder heat transfer coefficient in the case of different test conditions because of being favorable models on the SI engine operations. The evaluations show that the in-cylinder heat transfer characteristics of the air-cooled SI engine strongly depend on the load while they slightly depend on the spark timing.

Energy Economy With a Variable Speed Drive in an Oxygen Trim Controlled Boiler House

This paper investigates the potentional for energy saving in a boiler house that can be achieved through installing a variable speed drive (VSD) for the fan motor by including an oxygen trim control cycle. This investigation is carried out through surveys; energy saving calculations are based on experimental data. In particular, some unique energy saving measures and energy efficiency improvements in the boiler associated with the VSD system are analytically and experimentally studied. In this study, the relation between excess air ratio and boiler efficiency was investigated in a water tube boiler that has the capacity of producing 55 tons of steam per unit time at 245°C and 20 bar pressure. The boiler combustion air is supplied from a fan driven by a 30 kW 1450 rpm induction motor. Since the fan motor running at nominal speed has supplied the same airflow rate, excess air amount and exhaust gas temperature were very high at low loads. The boiler efficiency was low due to thermal energy losses and also consequently led to electrical energy losses. After implementation of the VSD, stack temperature was reduced from 200°C to 142°C, so the boiler efficiency was increased about 2.5% and 8000 kWh of electrical energy were saved in a month. The energy losses associated with excess air rate and its cost to manufacturers are evaluated and quantified. An overview and analysis of such conservation measures, along with the potential energy and cost savings, the implementation cost, and simple payback period are also given.

Selection of compressors for petrochemical industry in terms of reliability, energy consumption and maintenance costs examining different scenarios

In this study, based on some important criteria, qualitative and quantitative evaluations were presented for the selection of compressors used in compressed air systems, in a petrochemical industry. Four different scenarios were investigated according to the main criteria considered for the selection of the compressors such as reliability, energy efficiency, investment, and maintenance costs. The types of compressor and their capacities were analyzed and compared. In Scenario I, the currently active electrically driven compressors were considered as backup compressors, instead of them, a new unit turbo compressor and two units of VSD screw compressors were purchased as active compressors. In this scenario, the initial investment cost is low and standby steam consumption is reduced due to the fact that the backup compressors are electrically driven. In Scenario II all active and backup compressors are replaced by a new one, which is proposed to be electrically driven. In this scenario, the initial investment cost is high, but energy consumption is very low. In Scenario III, all active compressors are planned to be replaced by new backup steam-driven compressors. In this scenario, although the initial investment costs and energy consumption are high, the reliability of this scenario is higher than the reliability of Scenarios I and II. In Scenario IV, all compressors are projected to be replaced by new and equivalent compressors. In this scenario, the initial investment cost and energy consumption are high, but the reliability of this scenario is the highest comparing all other scenarios. The aim of this study is to contribute the studies on the selection of compressors by considering some important parameters as their types and capacities, in particular, for industrial enterprises that have risk of explosion like in the petrochemical industry.

Energy Conservation in Boiler House by Using Variable Speed Control

ABSTRACT Boilers should always be supplied with more combustion air than theoretically required in order to ensure complete combustion and safe operation. At the same time, boiler efficiency is very dependent on the excess air rate. Therefore, the excess air should be optimized to increase the system efficiency. In this study, the effect of the excess air ratio on the efficiency of the boiler system was investigated in a water tube boiler that has the capacity of producing 20 bar pressure and 55 ton steam at 245°C. The boiler combustion air is supplied from a fan driven by a 30kW at 1450 rpm induction motor. Since the fan motor, running at nominal speed, has supplied the same air flow rate, excess air amount and exhaust gas temperature were very high at low loads. In that stage, boiler efficiency was low due to thermal energy losses, which also consequently leads to electrical energy losses. The steam requirement of the factory changes because of the tire process. For example, in the tire cooking machines...