Modelling, Analyses and Optimization for Exergy Performance of an Irreversible Intercooled Regenerated Brayton CHP Plant: Part 2 — Performance Optimization

In the Part 1 of this paper, a variable temperature heat reservoir irreversible intercooling regenerative Brayton combined heat and power (CHP) plant model is set up, and the exergy efficiency and exergy output rate formulae are obtained. The optimization of pressure ratios and the influence analyses of some vital parameters on the exergy performances are carried out. In this Part, the heat conductance distributions about the high temperature-side heat exchanger, regenerator, intercooler, thermal consumer exchanger and low temperature-side heat exchanger, and the pressure ratios are optimized step by step. The effects of main parameters (such as of turbine and compressor efficiencies, working substance pressure drop loss, heat consumer required temperature, and so on) on the optimum exergy performances are investigated, and the heat capacitance rate matching between the heat reservoirs and working substance is studied.

Download Full-text

Modelling, Analyses and Optimization for Exergy Performance of an Irreversible Intercooled Regenerated Brayton CHP Plant: Part 1 — Thermodynamic Modelling and Parametric Analyses

Volume 6: Energy ◽

10.1115/imece2017-70045 ◽

2017 ◽

Cited By ~ 2

Author(s):

Lingen Chen ◽

Bo Yang ◽

Huijun Feng ◽

Zemin Ding

Keyword(s):

Heat Exchangers ◽

Variable Temperature ◽

Pressure Ratio ◽

Exergy Efficiency ◽

Heat Reservoir ◽

Output Rate ◽

Rate Versus ◽

Optimum Heat ◽

Set Up ◽

Parametric Analyses

A variable-temperature heat reservoir irreversible intercooling regenerated Brayton combined heat and power (CHP) plant model is set up in this paper. The model considers the heat transfer losses in all the heat exchangers, the working substance pressure drop loss in the piping, and the expansion and compression losses in turbine and compressor. Exergy output rate and exergy efficiency are considered as the research targets, and their analytical formulae are obtained. The optimal performances are gotten by optimizing the intercooled pressure ratio and total pressure ratio. The influences of some important parameters on the performances are studied in detail. Besides, the relation of exergy output rate versus exergy efficiency is investigated, and the curve is loop-shaped one. The results indicate that optimum heat capacity rate matching between the heat reservoir and working substance, and optimum heat consumer required temperature exist respectively, which generate double-maximal exergy output rate and double-maximal exergy efficiency, respectively. The heat conductance allocation optimization of all the heat exchangers will be carried out in Part 2 of this paper.

Download Full-text

Performance Optimization of Compact Ceramic High Temperature Heat Exchangers

Volume 3: Turbo Expo 2007 ◽

10.1115/gt2007-27888 ◽

2007 ◽

Author(s):

Q. Y. Chen ◽

M. Zeng ◽

D. H. Zhang ◽

Q. W. Wang

Keyword(s):

Heat Transfer ◽

High Temperature ◽

Heat Exchanger ◽

Performance Optimization ◽

Heat Exchangers ◽

Radiation Heat Transfer ◽

Surface Radiation ◽

Radiation Heat ◽

High Temperature Side ◽

Temperature Heat

In the present paper, the compact ceramic high temperature heat exchangers with parallel offset strip fins and inclined strip fins (inclined angle β = 0∼70°) are investigated with CFD method. The numerical simulations are carried out for high temperature (1500°C), without and with radiation heat transfer, and the periodic boundary is used in transverse direction. The fluid of high temperature side is the standard flue gas. The material of heat exchanger is SiC. NuS-G.R(with surface and gaseous radiation heat transfer) is averagely higher than NuNo.R (without radiation heat transfer) by 7% and fS-G.R is averagely higher than fNo.R by 5%. NuS-G.R(with surface and gaseous radiation heat transfer) is averagely higher than NuS.R (with only surface radiation heat transfer) by 0.8% and fS-G.R is averagely higher than fS.R by 3%. The thermal properties have significantly influence on the heat transfer and pressure drop characteristics, respectively. The heat transfer performance of the ceramic heat exchanger with inclined fins (β = 30°) is the best.

Download Full-text