scholarly journals Effect of Different Working Fluids on Shell and Tube Heat Exchanger to Recover Heat from Exhaust of An Automotive Diesel Engine

Author(s):  
S.N. Hossain ◽  
S Bari
2015 ◽  
Vol 77 (27) ◽  
Author(s):  
Omid Rowshanaie ◽  
Saari Mustapha ◽  
Kamarul Arifin Ahmad ◽  
Hooman Rowshanaie

A simulation model of Organic Rankine Cycle (ORC) was developed with HYSYS software driven by R245fa, with NOVEC7000 and R141b as working fluids and Fluegas of boilers as a heat source of shell and tube Heat Exchanger to generate large scale electricity. The initial working condition was in subcooled liquid and steady state condition. R141b was found to generate the highest electricity power increment in specific mass flow rates and inlet pressures of Expander because of approaching its critical temperature to inlet Fluegas temperature. Howeever, in terms of economic considerations and cost of shell and tube Heat Exchanger that related to total heat transfer capacity, NOVEC7000 is the optimum selection. Furthermore, R245fa has the highest total effiiciency of ORC compared with other working fluids in this study.


Author(s):  
Shekh N. Hossain ◽  
S. Bari

High temperature diesel engine exhaust gas can be an important source of heat to operate a bottoming Rankine cycle to produce additional power. In this research, an experiment was performed to calculate the available energy in the exhaust gas of an automotive diesel engine. A shell and tube heat exchanger was used to extract heat from the exhaust gas, and the performance of two shell and tube heat exchangers was investigated with parallel flow arrangement using water as the working fluid. The heat exchangers were purchased from the market. As the design of these heat exchangers was not optimal, the effectiveness was found to be 0.52, which is much lower than the ideal one for this type of application. Therefore, with the available experimental data, the important geometric aspects of the heat exchanger, such as the number and diameter of the tubes and the length and diameter of the shell, were optimized using computational fluid dynamics (CFD) simulation. The optimized heat exchanger effectiveness was found to be 0.74. Using the optimized heat exchangers, simulation was conducted to estimate the possible additional power generation considering 70% isentropic turbine efficiency. The proposed optimized heat exchanger was able to generate 20.6% additional power, which resulted in improvement of overall efficiency from 30% to 39%. Upon investigation of the effect of the working pressure on additional power generation, it was found that higher additional power can be achieved at higher working pressure. For this particular application, 30 bar was found to be the optimum working pressure at rated load. The working pressure was also optimized at part load and found that 2 and 20 were the optimized working pressures for 25% and 83% load. As a result 1.8% and 13.3% additional power were developed, respectively. Thus, waste heat recovery technology has a great potential for saving energy, improving overall engine efficiency, and reducing toxic emission per kilowatt of power generation.


Author(s):  
Ashok S Hadli ◽  
◽  
S. A. Alur ◽  
D.D. Chillal ◽  
N. R Banapurmath ◽  
...  

Most of the researchers have claimed that high compression engines (diesel engines) are performing slightly above of 1/3rd of their potential and remaining heat energy is wasted in the form of exhaust gas. Efforts are going on to improve the design of these engines and investigations are being carried out to recover this waste energy from exhaust gases and utilize for different applications.In the present work, initially water is used as a heat exchange medium for three different loads on diesel engine viz., 50%, 60% and 70%, which extracts heat energy to evaluate the exhaust heat attainable from exhaust gases of the engine. The exhaust gas is passed through the tube side of the heat exchanger which is obtained from an exhaust manifold of a four stroke single cylinder diesel engine. Water is passed through the shell side of the shell and tube heat exchanger. Later this work is repeated for two different cooling medium i.e. water-ethylene glycol mixtures with 25% and 50%. The results are compared for 60% engine load conditions. The counter flow type heat exchanger arrangement is considered for the analysis. The temperatures were recorded for hot gases and cold medium at inlet and outlet points of the shell side and tube side flow. Heat calculations are carried out for each combination and detailed in the result–discussion and conclusion chapter. The objective of this work is to assess the exhaust gas heat recovery capacity using the ethylene glycol-water mixture and come out with a mixture for higher heat recovery capacity. This work is undertaken with segmental baffle heat exchanger of zero degree inclination. Also the work is repeated for inclined baffle heat exchangers of 10-degree and 20-degree baffle inclination to assess the effectiveness of liquid in recovering the heat from exhaust gases. It is observed that the water and Ethylene glycol mixtures have performed satisfactorily in all three baffle setups showing only 1.5% - 2.0% less heat recovery when compared with only water.


Author(s):  
A. Adeyanju Anthony ◽  
K. Manohar

The study utilized the exhaust gas from a diesel engine to preheat water in the constructed shell and tube heat exchanger. The theoretical analysis of the heat exchanger was carried out using the Log Mean Temperature Difference (LMTD) method. The Volumetric flowrate of the water was manipulated using a valve and the resulting output temperature of water leaving the heat exchanger was recorded. Experimentation was carried out to determine the effects of volumetric flow rate on the output temperature and the effectiveness of the heat exchanger. After the test and data analysis, it was discovered that that at flow rate of 3.0 Liter per minute (LPM) the effectiveness of the heat exchanger was peak at 43.34%. The volumetric flow rate of water is inversely proportional to the output temperature of water and it was also established that the effectiveness of the heat exchanger depends on output temperature of and the mass flow rate of the water. Also it was proven that by preheating water before it enters the boiler of the Rankine cycle the efficiency of the cycle increases.


Author(s):  
Leonardo Cavalheiro Martinez ◽  
Leonardo Cavalheiro Martinez ◽  
Viviana Mariani ◽  
Marcos Batistella Lopes

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