Exergy Analysis of Various Absorption Heat Transformer Systems Using Classical and Modified Gouy–Stodola Equation

2015 ◽  
Vol 23 (01) ◽  
pp. 1550006 ◽  
Author(s):  
T. Goel ◽  
G. Sachdeva
Keyword(s):  
Exergy Analysis ◽  
Waste Heat ◽  
Lithium Bromide ◽  
Second Law ◽  
Operating Parameters ◽  
Classical Approach ◽  
Exergy Destruction ◽  
Second Law Analysis ◽  
Heat Transformer ◽  
Study Performance

In the present study, performance evaluation of three different configurations of absorption heat transformer (AHT) is carried out by supplying the waste heat of same mass and same temperature; and exergy analysis is done using both the classical and modified Gouy–Stodola equation. For this a mathematical model is developed for all the three arrangements in Engineering Equation Solver. Water–lithium bromide is used as a working pair. The results of exergy destruction with classical and modified Gouy–Stodola equation are compared for different systems. Further various operating parameters are varied to predict the performance of the systems on the basis of second law analysis. The result showed that the amount of hot fluid produced in absorber is more for system 3 as compared to other configurations. The irreversibility calculated by the modified approach comes out to be 25.78%, 23.60%, and 23.45% more than the exergy destruction obtained by the classical approach in the three cases, respectively. Thus, there is a need to employ the modified approach of Gouy–Stodola equation for calculating the real irreversibility which helps in predicting the scope of improvement and the performance of the system more accurately.

EXERGY ANALYSIS OF A VAPOR ABSORPTION HEAT TRANSFORMER USING MODIFIED GUOY–STODALA EQUATION

2014 ◽  
Vol 22 (03) ◽  
pp. 1450019 ◽  
Author(s):  
J. PASTOR ◽  
G. SACHDEVA ◽  
R. BILASH
Keyword(s):  
Heat Exchange ◽  
System Performance ◽  
Exergy Analysis ◽  
Lithium Bromide ◽  
Computer Programme ◽  
Classical Approach ◽  
Exergy Destruction ◽  
Vapor Absorption ◽  
Quantitative Results ◽  
Heat Transformer

In the present work, thermodynamic analysis of a Lithium bromide–water-based absorption heat transformer (AHT) is done using a mathematical model. The study includes exergy analysis with the introduction of external fluid arrangements working as the interface of heat exchange for the various components of the model. Quantitative results are obtained for a set of inputs and modified Guoy–Stodala equation is used to include the real heat exchange temperatures in the study. These results are compared to the classical approach. It is observed that the total irreversibility calculated by the modified approach comes out to be 26.1% more than the exergy destruction obtained by the classical approach. Next, different operating parameters are varied to understand the effect of these on exergy destruction using a computer programme code. Thus, a conclusion is drawn in the form of graphs, as to how the system performance can be improved. Using the concept of irreversibility, the study finds that the performance of the system can be enhanced by decreasing the temperature of evaporator and generator or by increasing the temperature of condenser and absorber.

scholarly journals Exergy Analysis of Integrated Gas-Steam Cycle

1994 ◽  
Author(s):  
Onkar Singh ◽  
R. Yadav
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Second Law Of Thermodynamics ◽  
Heat Recovery Boiler ◽  
Second Law ◽  
Operating Parameters ◽  
Insight Into ◽  
Steam Cycle

The thermodynamic analysis of integrated gas/steam cycle has been carried out on the basis of second law of thermodynamics. The exergy analysis provides a viable understanding of the influence of various parameters on the distribution of losses in the constituent components of the cycle. The paper also provides the insight into the influence of changing operating parameters on the performance of the waste heat recovery boiler, which in turn questions the viability of the integrated gas/steam cycle.

Exergy Analysis of a Solar Heating System

1995 ◽  
Vol 117 (3) ◽  
pp. 249-251 ◽  
Author(s):  
Geng Liu ◽  
Y. A. Cengel ◽  
R. H. Turner
Keyword(s):  
Exergy Analysis ◽  
Energy Analysis ◽  
Second Law Of Thermodynamics ◽  
Heating System ◽  
Solar Heating ◽  
Second Law ◽  
Exergy Destruction ◽  
Thermal Systems ◽  
Heating Systems ◽  
Second Law Analysis

Exergy destruction associated with the operation of a solar heating system is evaluated numerically via an exergy cascade. As expected, exergy destruction is dominated by heat transfer across temperature differences. An energy analysis is also given for comparison of exergy cascade to energy cascade. Efficiencies based on both the first law and second law of thermodynamics are calculated for a number of components and for the system. The results show that high first-law efficiency does not mean high second-law efficiency. Therefore, the second-law analysis has been proven to be a more powerful tool in identifying the site losses. The procedure used to determine total exergy destruction and second law efficiency can be used in a conceptual design and parametric study to evaluate the performance of other solar heating systems and other thermal systems.

scholarly journals Conventional and Advanced Exergoeconomic Analysis of a Compound Ejector-Heat Pump for Simultaneous Cooling and Heating

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3511
Author(s):  
Ali Khalid Shaker Al-Sayyab ◽  
Joaquín Navarro-Esbrí ◽  
Victor Manuel Soto-Francés ◽  
Adrián Mota-Babiloni
Keyword(s):  
Heat Pump ◽  
Exergy Analysis ◽  
Waste Heat ◽  
District Heating ◽  
Cost Comparison ◽  
Exergy Destruction ◽  
Pump System ◽  
Heat Pump System ◽  
Destruction Rate ◽  
Exergoeconomic Analysis

This work focused on a compound PV/T waste heat driven ejector-heat pump system for simultaneous data centre cooling and waste heat recovery for district heating. The system uses PV/T waste heat as the generator’s heat source, acting with the vapour generated in an evaporative condenser as the ejector drive force. Conventional and advanced exergy and advanced exergoeconomic analyses are used to determine the cause and avoidable degree of the components’ exergy destruction rate and cost rates. Regarding the conventional exergy analysis for the whole system, the compressor represents the largest exergy destruction source of 26%. On the other hand, the generator shows the lowest sources (2%). The advanced exergy analysis indicates that 59.4% of the whole system thermodynamical inefficiencies can be avoided by further design optimisation. The compressor has the highest contribution to the destruction in the avoidable exergy destruction rate (21%), followed by the ejector (18%) and condenser (8%). Moreover, the advanced exergoeconomic results prove that 51% of the system costs are unavoidable. In system components cost comparison, the highest cost comes from the condenser, 30%. In the same context, the ejector has the lowest exergoeconomic factor, and it should be getting more attention to reduce the irreversibility by design improving. On the contrary, the evaporator has the highest exergoeconomic factor (94%).

Second Law Analysis of Spray Evaporation

1990 ◽  
Vol 112 (2) ◽  
pp. 130-135 ◽  
Author(s):  
S. K. Som ◽  
A. K. Mitra ◽  
S. P. Sengupta
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Entropy Generation ◽  
Exergy Analysis ◽  
Droplet Evaporation ◽  
Second Law ◽  
Hot Gas ◽  
Second Law Analysis ◽  
Initial Drop ◽  
Parallel Stream

A second law analysis has been developed for an evaporative atomized spray in a uniform parallel stream of hot gas. Using a discrete droplet evaporation model, an equation for entropy balance of a drop has been formulated to determine numerically the entropy generation histories of the evaporative spray. For the exergy analysis of the process, the rate of heat transfer and that of associated irreversibilities for complete evaporation of the spray have been calculated. A second law efficiency (ηII), defined as the ratio of the total exergy transferred to the sum of the total exergy transferred and exergy destroyed, is finally evaluated for various values of pertinent input parameters, namely, the initial Reynolds number (Rei = 2ρgVixi/μg) and the ratio of ambient to initial drop temperature (Θ∞′/Θi′).

Teaching Power Cycles by Comparative First- and Second-Law Analysis of Their Evolution

1997 ◽  
Vol 25 (1) ◽  
pp. 13-31 ◽  
Author(s):  
William R. Dunbar ◽  
Noam Lior
Keyword(s):  
Power Plants ◽  
Exergy Analysis ◽  
Energy Analysis ◽  
Energy Systems ◽  
Thermal Engineering ◽  
Second Law ◽  
Intellectual Curiosity ◽  
Educational Approach ◽  
Power Cycles ◽  
Second Law Analysis

The teaching of power cycles in courses of thermodynamics or thermal engineering was traditionally based on first-law analysis. Second-law analysis was typically taught later, and not integrated with it. This approach leaves the student ignorant of the effect of operating parameters and cycle modifications on the accompanying exergy (availability) magnitudes and component irreversibilities, which are necessary for evaluating the potential for further system improvements. It also leaves many of the students with an ambiguous understanding of the exergy concept and its use. Consonant with the gradual changes in this educational approach, which increasingly attempt to integrate first- and second-law analysis, this paper recommends a strategy which integrates exergy analysis into the introduction and teaching of energy systems, demonstrated and made didactically appealing by an examination of the historical evolution of power plants, emphasizing the objectives for improvements, accomplishments, constraints, and consequently the remaining opportunities. Important conclusions from exergy analysis, not obtainable from the conventional energy analysis, were emphasized. It was found that this approach evoked the intellectual curiosity of students and increased their interest in the course.

Second law analysis of novel working fluid pairs for waste heat recovery by the Kalina cycle

Energy ◽  
2017 ◽  
Vol 119 ◽  
pp. 188-198 ◽  
Author(s):  
Tim Eller ◽  
Florian Heberle ◽  
Dieter Brüggemann
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Working Fluid ◽  
Second Law ◽  
Kalina Cycle ◽  
Second Law Analysis
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