scholarly journals Performance and environment interactivity of concentric heat exchanger practicing TiO2 nanofluid and operated near heat capacity ratio of unity

2021 ◽  
Vol 28 ◽  
pp. 101702
Author(s):  
Saad Alshahrani ◽  
Esam I. Jassim ◽  
Faizan Ahmed ◽  
Bashar I. Jasem
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Capacity Ratio

THE ANALYSIS OF EXERGY EFFICIENCY IN THE LOW TEMPERATURE HEAT EXCHANGER

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3497-3499 ◽  
Author(s):  
LAN PENG ◽  
YOU-RONG LI ◽  
SHUANG-YING WU ◽  
BO LAN
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Low Temperature ◽  
Transfer Process ◽  
Heat Exchangers ◽  
Heat Transfer Process ◽  
Exergy Efficiency ◽  
Capacity Ratio ◽  
Temperature Heat

Based on the analyzing of the thermodynamic performance of the heat transfer process in the low temperature heat exchangers, the exergy efficiency of the heat transfer process is defined and a general expression for the exergy efficiency is derived, which can be used to discuss the effect of heat transfer units number and heat capacity ratio of fluids on the exergy efficiency of the low temperature heat exchanger. The variation of the exergy efficiency for several kinds of flow patterns in the low heat exchangers is compared and the calculating method of the optimal values of heat capacity ratio for the maximum exergy efficiency is given.

Heat capacity ratio and the best type of heat exchanger for geothermal water providing maximum heat transfer

Energy ◽  
2015 ◽  
Vol 90 ◽  
pp. 1563-1568 ◽  
Author(s):  
Özden Ağra ◽  
Hasan Hüseyin Erdem ◽  
Hakan Demir ◽  
Ş. Özgür Atayılmaz ◽  
İsmail Teke
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Geothermal Water ◽  
Maximum Heat ◽  
Capacity Ratio ◽  
Maximum Heat Transfer

Effectiveness of 6-Row Crossflow Heat Exchangers Alternating Circuitry

Volume 3 ◽  
2004 ◽  
Author(s):  
Tony D. Chen
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
Fluid Temperature ◽  
Basic Tool ◽  
Capacity Ratio ◽  
Comparison Of Effectiveness ◽  
Air Conditioning Systems ◽  
Flow Maldistribution

Air-cooled heat exchangers with six tube rows are commonly seen in air-conditioning systems for large commercial and industry buildings. The analytical solutions of heat exchanger effectiveness for 6-row plate fin-and-tube heat exchangers with alternating circuitries have been derived and expressed explicitly in terms of heat capacity ratio, number of transfer units, and the dimensionless fluid temperature to the inlet of each row and section in this study. This set of exact solutions serve as a basic tool in designing heat exchanger circuitry to its most accurate effectiveness. Comparison of effectiveness between pure and alternating circuiting for 6-row crossflow heat exchangers shows that alternating circuiting could have less effectiveness than pure crossflow with identical circuiting from 1.0 to 7.9% for cases of NTUs range from 1.0 to 3.0 and capacity ratio of 0.5. Nevertheless, alternating circuit has its benefit of lowering the temperature difference between air- and refrigerant-flow, which leads to less pressure drop and less flow maldistribution, therefore resulting in better overall heat exchanger performance.

Analysis of heat capacity ratio on porous media in oscillating flow

2021 ◽  
Vol 179 ◽  
pp. 121724
Author(s):  
Armando Di Meglio ◽  
Elio Di Giulio ◽  
Raffaele Dragonetti ◽  
Nicola Massarotti
Keyword(s):  
Heat Capacity ◽  
Porous Media ◽  
Oscillating Flow ◽  
Capacity Ratio

Minimum Irreversibility Criteria for Heat Exchanger Configurations

1999 ◽  
Vol 121 (4) ◽  
pp. 241-246 ◽  
Author(s):  
F. E. M. Saboya ◽  
C. E. S. M. da Costa
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Mass Flow Rates ◽  
Flow Heat

From the second law of thermodynamics, the concepts of irreversibility, entropy generation, and availability are applied to counterflow, parallel-flow, and cross-flow heat exchangers. In the case of the Cross-flow configuration, there are four types of heat exchangers: I) both fluids unmixed, 2) both fluids mixed, 3) fluid of maximum heat capacity rate mixed and the other unmixed, 4) fluid of minimum heat capacity rate mixed and the other unmixed. In the analysis, the heat exchangers are assumed to have a negligible pressure drop irreversibility. The Counterflow heat exchanger is compared with the other five heat exchanger types and the comparison will indicate which one has the minimum irreversibility rate. In this comparison, only the exit temperatures and the heat transfer rates of the heat exchangers are different. The other conditions (inlet temperatures, mass flow rates, number of transfer units) and the working fluids are the same in the heat exchangers.

Computation of Acoustic Velocity of Natural Gases With an Alternative Heat Capacity Ratio Equation and Application to Seismic Modeling

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Romulo Carvalho ◽  
Fernando Moraes
Keyword(s):  
Heat Capacity ◽  
Equations Of State ◽  
Acoustic Velocity ◽  
Fluid Composition ◽  
Seismic Modeling ◽  
Data Set ◽  
Natural Gases ◽  
Single Interface ◽  
Capacity Ratio ◽  
Extensive Experimental Data

Abstract We investigate three formulations for computing acoustic velocity of natural gas and derive an equation for the heat capacity ratio, which plays a central role in these formulations. The first formulation is a compilation of fundamental equations available in the engineering literature, referred to as the DASH formulation. The second formulation is a development from the first, in which we use the derived equation for the heat capacity ratio (modified DASH). The third formulation is a mainstream method implemented in Geoscience (BW formulation). All three formulations stem from virial Equations of State that take preponderance in the exploration stage, when the detailed fluid composition is unknown and compositional methods are frequently inapplicable. We test the formulations on an extensive experimental data set of acoustic velocity of natural gases and compare the resulting accuracies. Both DASH and modified DASH formulations provide significantly higher accuracy when compared to the BW formulation. Additionally, the modified DASH, as we derive in this work, has the highest accuracy at pressures above 7000 psi, a condition typically encountered in the Brazilian pre-salt reservoirs. In a final step, we investigate how these different formulations and corresponding accuracies in velocity computation may affect seismic modeling, using a single interface model between a dense gas reservoir and a sealing rock. A direct comparison of amplitude versus offset modeling using our modified DASH formulation and the BW formulation shows up to 50% difference in amplitude calculation in a sensitivity exercise, especially at the longer offsets and higher pressures.

Applying the X-Ratio Correction to Calculated Air Heater Efficiency: An Alternate Method

2010 ◽  
Author(s):  
David C. McLaughlin ◽  
Joseph R. Nasal
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Correction Factor ◽  
Mass Flow ◽  
Flue Gas ◽  
Correction Method ◽  
Gas Temperature ◽  
Original Design ◽  
Air Heater ◽  
The Impact

ASME PTC 4.3 on testing Air Heaters provides guidance for the calculation of gas-side efficiency as a measure of air heater performance. This code also provides for calculation of air heater X-ratio (XR), which is the ratio of the heat capacity (mass flow times specific heat capacity) of the air flowing through the heater to that of the flue gas. The code acknowledges the impact of XR on air heater efficiency, and dictates that the gas temperature leaving the air heater (and hence, air heater efficiency) be corrected for deviation from design XR by the use of “appropriate design correction curves” [1]. Unfortunately, such curves are rare, and therefore this important correction is usually ignored in routine air heater test calculations by power plant testing personnel, resulting in an incorrect calculation of air heater efficiency. This is particularly true for balanced draft boilers burning coal that are aged and have a significant amount of air leakage into the boiler setting. On these boilers, the ratio of combustion flue gas mass flow to combustion air mass flow is changed significantly from the original design, and therefore applying an XR correction factor is essential to calculating and reporting accurate air heater efficiency. This paper presents a method to calculate and correct for a deviation from design X-ratio based on standard heat exchanger analysis techniques, namely the ε-NTU method, which utilizes the concept of heat exchanger effectiveness (ε). A solution that results in applying the ratio of the design to actual XR’s as the correction factor is developed. The paper also provides empirical data from testing on a coal-fired boiler to validate the alternate correction method.

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