scholarly journals Optimization of operating parameters a heat-recovery exchanger of a boiler plant based on the exergy approach

2021 ◽  
pp. 5-16
Author(s):  
N. Fialko ◽  
◽  
A. Stepanova ◽  
R. Navrodskaya ◽  
S. Shevchuk ◽  
...  
Keyword(s):  
Moisture Content ◽  
Heat Recovery ◽  
Reynolds Numbers ◽  
Exergy Efficiency ◽  
Parameters Optimization ◽  
Final Moisture Content ◽  
Operating Parameters ◽  
Exhaust Gases ◽  
Air Heating ◽  
Content Ratio

Abstract. The results of operating parameters optimization of the air-heating heat-recovery exchanger of complex heat recovery system of a gas-fired boiler designed for heating water and blown air are presented. Air heating in this heat-recovery exchanger is realized by deep cooling of the waste exhaust gases, that is, with a change in their moisture content during the heat recovery process. The possibilities of using a complex technique based on the structural-variant method and exergy analysis methods for the optimization of the heat-recovery exchanger are analyzed. The developed structural scheme of the boiler plant with identification of input and output exergy streams for all elements of the installation is presented. The change of exergy losses in this heat-recovery exchanger has a rather strong effect on the change of the whole heat recovery system efficiency is established. Thus, the optimization of heat-recovery exchanger operating parameters of is a necessary condition for increasing the efficiency of heat recovery in general. The choice of multiplicative exergy efficiency criteria used as target functions of operating parameters optimization of the investigated air-heating heat exchanger is substantiated. The obtained dependences of exergy efficiency criteria on the operating parameters of the heat-recovery exchanger, such as the ratio of the Reynolds numbers of exhaust gases and air and the ratio of the initial and final moisture content of exhaust gases, are analyzed. It is established that the minimum values of the efficiency criteria, which corresponds to the maximum exergy efficiency, is observed in the range of values of the ratio of the initial and final moisture content of exhaust gases in the range from 2.4 to 3.0. It is shown that at a value of the specified ratio of 2.7, the exergy efficiency of the investigated heat-recovery exchanger does not depend on the ratio of the Reynolds numbers of exhaust gases and air. It is established that of initial and final moisture content ratio of exhaust gases, equal to 2.7, and the Reynolds numbers ratio of exhaust gases and air, equal to 0.8 and 1.2, depending on the values of initial and final moisture content ratio of exhaust gases, can be taken as the optimal values of the operating parameters. Key words: heat-recovery exchangers, exergy efficiency, complex techniques

Optimization of geometric parameters and analysis of exergy efficiency of heat recovery units glass furnaces

2021 ◽  
pp. 5-17
Author(s):  
N. Fialko ◽  
◽  
A. Stepanova ◽  
R. Navrodska ◽  
S. Shevchuk ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Glass Melting ◽  
Exergy Efficiency ◽  
Geometric Parameters ◽  
Hot Water ◽  
Air Heating ◽  
Heat Exchange Surface ◽  
Exchange Surface

The paper presents the results of optimization of the geometric parameters of the heat exchange surface of water and air-heating heat exchangers of glass-making furnaces and an analysis of their exergy efficiency. Ensuring the efficient operation of heat recovery units in various thermal circuits is an urgent problem of heat power engineering. The aim of the work is to establish the optimal areas of the geometric parameters of the heat exchange surface of heat recovery units of glass-melting furnaces and to analyze their exergy efficiency. The paper presents the results of solving the tasks necessary to achieve the goal: - using statistical methods for planning the experiment, determine the levels of variation of the parameters of the geometric surface of heat transfer for the heat recovery units under study and calculate the values of the criteria for evaluating the efficiency at the points of the central orthogonal compositional plan; - to obtain the regression equations for the investigated heat exchangers, to determine the optimal areas of change in the geometric parameters of the heat exchange surface and the corresponding exergy efficiency criteria. To determine the optimal areas of geometric parameters of the heat exchange surface, a complex methodology is used based on the methods of exergy analysis and statistical methods of the theory of experiment planning. It has been established that when designing heat recovery schemes for heating water in heat supply systems and for heating blast air, heat recovery units with the following values of the areas of variation of the geometric parameters of the heat exchange surface can be used: - the values of the area of variation of the distance between the panels for heat recovery units with a staggered and corridor arrangement of pipes in a bundle s1 = 58.0-62.0 mm. - the values of the areas of change in the diameter of pipes for a hot water heat exchanger with a corridor arrangement of pipes d = 41.0-43.0 mm and for an air heating heat exchanger with a staggered and corridor arrangement of pipes d = 29.0-31.0 mm. - the use of the values of the ranges of change of other parameters is carried out taking into account additional technological factors. It has been established that the exergy efficiency of hot water heat recovery units is in all cases higher than the exergy efficiency of air heating units. For hot water heat exchangers, the values of exergy criteria are lower than for air heating ones: k – 2.0 times, ε – by 7.5%, m0 – 1.9 times. The expediency of using the investigated heat recovery units in heat recovery circuits of glass melting furnaces has been established, taking into account the results obtained and in the presence of certain technological factors. The results obtained and further developments in the field of optimization of the operating parameters of heat recovery units for glass-melting furnaces will provide an increase in the efficiency of heat recovery equipment for power plants.

Effects of Drying Conditions, Final Moisture Content, and Degree of Milling on Rice Flavor

1997 ◽  
Vol 74 (5) ◽  
pp. 566-570 ◽  
Author(s):  
Elaine T. Champagne ◽  
Karen L. Bett ◽  
Bryan T. Vinyard ◽  
Bill D. Webb ◽  
Anna M. McClung ◽  
...  
Keyword(s):  
Moisture Content ◽  
Final Moisture Content ◽  
Degree Of Milling ◽  
Drying Conditions ◽  
Rice Flavor

Design of a heat recovery unit using exhaust gases for energy savings in an absorption air conditioning unit

2021 ◽  
pp. 117031
Author(s):  
Mostafa El-Shafie ◽  
M. Khalil Bassiouny ◽  
Shinji Kambara ◽  
Samy M. El-Behery ◽  
A.A. Hussien
Keyword(s):  
Air Conditioning ◽  
Heat Recovery ◽  
Energy Savings ◽  
Exhaust Gases ◽  
Recovery Unit

scholarly journals Energy and Exergy Analyses of Tube Banks in Waste Heat Recovery Applications

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2094 ◽  
Author(s):  
Mustafa Erguvan ◽  
David MacPhee
Keyword(s):  
Energy Efficiency ◽  
Reynolds Number ◽  
Heat Recovery ◽  
Waste Heat ◽  
Cross Flow ◽  
Exergy Efficiency ◽  
Circular Cylinders ◽  
Published Data ◽  
Energy And Exergy ◽  
Exergy Analyses

In this study, energy and exergy analyses have been investigated numerically for unsteady cross-flow over heated circular cylinders. Numerous simulations were conducted varying the number of inline tubes, inlet velocity, dimensionless pitch ratios and Reynolds number. Heat leakage into the domain is modeled as a source term. Numerical results compare favorably to published data in terms of Nusselt number and pressure drop. It was found that the energy efficiency varies between 72% and 98% for all cases, and viscous dissipation has a very low effect on the energy efficiency for low Reynolds number cases. The exergy efficiency ranges from 40–64%, and the entropy generation due to heat transfer was found to have a significant effect on exergy efficiency. The results suggest that exergy efficiency can be maximized by choosing specific pitch ratios for various Reynolds numbers. The results could be useful in designing more efficient heat recovery systems, especially for low temperature applications.

Stability of Thiamine and Riboflavin During Extrusion Processing of Triticale

1976 ◽  
Vol 39 (4) ◽  
pp. 244-245 ◽  
Author(s):  
G. BEETNER ◽  
T. TSAO ◽  
A. FREY ◽  
K. LORENZ
Keyword(s):  
Moisture Content ◽  
Multiple Regression ◽  
Temperature Effects ◽  
Initial Moisture Content ◽  
Final Moisture Content ◽  
Whole Grain ◽  
Moisture Contents ◽  
Extrusion Processing ◽  
Nozzle Size ◽  
The Relationship

Triticale kernels were extruded using a Brabender Plasticorder extruder with ¾-inch rifled barrel and 1:1 flight depth ratio screw. Whole grain samples were extruded at initial moisture contents of 15, 20, and 25%. Debranned samples were extruded at an initial moisture content of 22%. Barrel temperatures of 350, 400, and 450 F and nozzle openings of 1/8 inch and 1/16 inch were used. The products were analyzed for thiamine and riboflavin content. Results were corrected for final moisture content and expressed as fraction retained. A multiple regression was done to determine the relationship between independent and derived variables, and the retention. Riboflavin retention was correlated simply as a function of barrel temperature. Thiamine retention of the debranned material was correlated as a function of nozzle size and barrel temperature. Thiamine retention of the whole grain samples was correlated for nozzle size, first and second order temperature effects, and confounding between nozzle size and temperature.

scholarly journals Operating parameters affecting the thermal performance of biomass boilers

TAPPI Journal ◽  
2017 ◽  
Vol 16 (08) ◽  
pp. 453-461
Author(s):  
Naz Orang ◽  
Honghi Tran ◽  
Andy Jones ◽  
F. Donald Jones
Keyword(s):  
Moisture Content ◽  
Thermal Performance ◽  
Excess Oxygen ◽  
Operating Parameters ◽  
Pulp Mills ◽  
Furnace Temperature ◽  
Bubbling Fluidized Bed ◽  
Oil Flow ◽  
Induced Draft Fan ◽  
Content Range

Operating data of a bubbling fluidized bed (BFB) boiler and three stoker grate (SG) biomass boilers from different pulp mills were analyzed over a 2-year period. The results show that in all cases, the thermal performance decreases markedly from 5.5 to 4 lb steam/lb dry biomass as the feedstock moisture content increases from 40% to 60%. The BFB boiler had better thermal performance, although it operated in a higher moisture content range compared with the SG boilers. Multivariate analysis was also performed on one of the SG boilers to determine operating parameters that affect thermal performance. The results show that furnace temperature, oil flow rate, and induced draft fan current positively correlate with thermal performance, while the feedstock moisture content, total air flow, and excess oxygen (O2) negatively correlate with thermal performance. This implies that when making modifications to improve thermal performance, it is important to take into account correlations among various parameters. In some cases, one positively correlated parameter might cause an increase in a negatively correlated parameter. The net effect might be a decrease in thermal performance.

scholarly journals Evaluation and analysis of exergoeconomic performance for the calcination process of green petroleum coke in vertical shaft kiln

2021 ◽  
pp. 294-294
Author(s):  
Peng Li ◽  
Baokuan Li ◽  
Zhongqiu Liu ◽  
Wenjie Rong
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Shaft Furnace ◽  
Exergy Efficiency ◽  
Heat Recovery Boiler ◽  
Vertical Shaft ◽  
Exergy Destruction ◽  
Calcination Process ◽  
Recovery Boiler

The main objective of this paper is to establish a mathematical framework to analyze the complex thermal economic performance of the calcination process. To find the factors affecting exergy efficiency loss, different exergy destruction is investigated in detail. Furthermore, the exergy flow cost model for exergy cost saving has also been developed. The results show that the vertical shaft furnace is a self-sufficiency equipment without additional fuel required, but the overall exergy destruction accounts for 54.11% of the total exergy input. In addition, the energy efficiency of the waste heat recovery boiler and thermal deaerator are 83.52% and 96.40%, whereas the exergy efficiency of the two equipment are 65.98% and 94.27%. Furthermore, the import exergy flow cost of vertical shaft furnace, waste heat recovery boiler and thermal deaerator are 366.5197 RMB/MJ, 0.1426 RMB/MJ and 0.0020RMB/MJ, respectively. Based on the result, several suggestions were proposed to improve the exergoeconomic performance. Assessing the performance of suggested improvements, the total exergy destruction of vertical shaft furnace is reduced to 134.34 GJ/h and the exergy efficiency of waste heat recovery boiler is raised up to 66.02%. Moreover, the import exergy flow cost of the three different equipment is reduced to 0.0329 RMB/MJ, 0.1304 RMB/MJ and 0.0002 RMB/MJ, respectively.

scholarly journals Physical properties of sessile oak (quercus petraea l) used by the wood industry in Kosovo

2020 ◽  
Vol 2 (7) ◽  
pp. 278-285
Author(s):  
Rrahim Sejdiu ◽  
Florit Hoxha ◽  
Bujar Jashari ◽  
Lulzim Idrizi
Keyword(s):  
Specific Gravity ◽  
Moisture Content ◽  
Physical Properties ◽  
Radial Direction ◽  
Tangential Direction ◽  
Quercus Petraea ◽  
Sessile Oak ◽  
Content Ratio ◽  
Wet Condition ◽  
Shrinkage Coefficient

The paper shows some physical properties of sessile oak obtained in Kosovo regions. In the study are shown: wood shrinkage, specific gravity, shrinkage coefficient for 1% change of moisture content, ratio of shrinkage in tangential and radial direction etc. The amount of volumetric shrinkage of sessile oak is 15.95%, heartwood part has an average shrinkage 15.41% in The shrinkage of sapwood part is 17.56%. Specific gravity at: wet condition: (1.013gr/cm3); 12% (0.853gr/cm3) and 0% (0.826gr/cm3) of moisture content. Specific gravity of heartwood at: wet condition (1.05gr/cm3); 12% (0.88gr/cm3); 0% (0.85gr/cm3). The specific gravity of sapwood at: wet condition (0.91gr/cm3); 12% (0.77gr/cm3); 0% (0.748gr/cm3). The ratio of average shrinkage between tangential and radial cutting direction is 1.71%. This ratio was significantly higher in sapwood than heartwood. Coefficient of shrinkage (changing 1% of moisture content) in the radial direction is 0.00196, and 0.00323 in tangential direction.  

Recovery and effective utilization of waste heat from the exhaust of internal combustion engines for cooling applications using ANSYS

2021 ◽  
pp. 095440622110568
Author(s):  
Ghulam Abbas Gohar ◽  
Muhammad Zia Ullah Khan ◽  
Hassan Raza ◽  
Arslan Ahmad ◽  
Yasir Raza ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Heat Recovery ◽  
Waste Heat ◽  
Internal Combustion ◽  
Heat Energy ◽  
Exit Velocity ◽  
Inlet Velocity ◽  
Exhaust Gases ◽  
Recovery Unit ◽  
Libr Solution

The exhaust gases from an internal combustion (IC) engine carry away about 75% of the heat energy which means only 25% of heat energy is operated for power production. A recovery unit at the exhaust outlet port can ensure heat exchange between different temperature fluids through conjugate heat transfer phenomena. This study represents heat recovery from exhaust gases that are emitted from IC engines which can be utilized in various applications such as vapor absorption refrigeration systems. In the present work, a new type of perforated fin heat exchanger for waste heat recovery of exhaust gases is designed using SolidWorks, and the flow field design of the heat recovery system is optimized using ANSYS software. Various parameters (velocity, pressure, temperature, and heat conduction) of hot and cold fluid have been analyzed. Inlet velocity of cold fluids including refrigerant (LiBr solution), water, and graphene oxide (GO) nanofluid have been adopted at 0.03 m/s, 0.165 m/s, and 0.3 m/s, respectively. Inlet velocity of hot fluid is taken as 2 m/s, 4 m/s, and 6 m/s, respectively, to develop a test matrix. The results showed that maximum temperature reduction by the exhaust is achieved at 104.8°C using graphene oxide nanofluids with an inlet velocity of 0.3 m/s and exit velocity of 2 m/s in the heat recovery unit. Similarly, temperature reduction by exhaust gases is acquired at 102 °C using water and 96.34 °C by using a refrigerant (LiBr solution) with the same exit velocity (2 m/ s). Furthermore, maximum effectiveness of 0.489 is also obtained for GO nanofluid when compared with water and the refrigerant. On the other hand, the refrigerant has the maximum log mean temperature difference from all fluids with a value of 224.4 followed by water and GO.

Sign in / Sign up

Export Citation Format

Share Document