Entransy analysis of tube arrangement effect on condenser performances and its application

Ji’An MENG; ZhiXin LI

doi:10.1360/N972015-00434

Chinese Science Bulletin

Download PDF

Chinese Science Bulletin, Volume 61, Issue 17: 1877-1888(2016) https://doi.org/10.1360/N972015-00434

Entransy analysis of tube arrangement effect on condenser performances and its application

Ji’An MENG, ZhiXin LI

More info

ReceivedApr 23, 2015
AcceptedMay 21, 2015
PublishedJun 30, 2015

Previous Table of Contents Next

Rating

Abstract

Condenser is a huge, complex shell-and-tube heat exchanger. It is the key auxiliary equipment in power plants whose designs have a very important influence on thermal efficiency of electric power generation. At present, power plant condensers are traditionally designed based on recommendations from previous designs and experimental results, often based on the standards developed by the Heat Exchange Institute. However, it does not take a number of factors into account, including the tube arrangement. Hence, to study the tube arrangement effect on condenser performance and to optimize/improve the condenser design are very important for energy saving. The condenser performances, such as the back pressure and venting rate, are strongly affected by the tube arrangement, and there are three irreversible processes for the fluid flow, heat transfer and mass diffusion in condenser. Borrowing from the entransy analysis method of heat transfer process, the momentum entransy analysis and mass entransy analysis were performed on the steam flow and air mass diffusion process in condenser. Adopting the porous media model the momentum entransy balance equation and the air mass entransy balance equation of the steam flow were deduced, then, the relation of momentum entransy loss of the steam flow and the distributed flow and heat transfer parameters in the condenser and the relation of air mass entransy increase of the steam flow and the distributed parameters of flow, heat transfer and air mass fraction were deduced. With the two relations the effects of tube arrangement on the back pressure and the venting rate are numerically investigated. The numerical analyses on four typical condensers indicate that larger momentum entransy loss relates to larger back pressure, and larger air mass entransy increase relates to less venting rate. Based on the numerical results of the four kinds of tube arrangements 330 MW condensers, the principles for tube layout in condenser are summarized. For examples, the reasonable design of the periphery of the tube bundle, i.e., the tube bundle profile, can lead the steam more uniformly entering the tube bundle, then the back pressure can be decreased; the tube arrangement should be well designed to properly guide the steam flow so as to avoid vortex flows, and a air cooling region should be well designed to reduce the venting rate. Finally, the bionic double-tree-shaped tube bundle condenser is introduced and the performances of a 330 MW condenser with bionic double-tree-shaped tube bundle are numerically analyzed. The results indicate that the steam uniformly enters the tube bundle, the thermal parameters are mainly centripetally distributed from the tube bundle periphery to the venting channel; the well-designed auxiliary steam entering channels result in a reduction of average steam velocity, hence, a reduction of flow resistance; The non-condensed steam is deeply condensed in the gradually contracted air cooling region, which strongly reduces the venting rate. Compared with the existing four kinds of condensers, its flow and thermal performances are much better. The back pressure of the rebuilt #2 condenser of Laicheng Power Plant by using the bionic double-tree-shaped tube bundle is decreased 1.5 kPa.

Funded by

国家重点基础研究发展计划(2013CB228301)

References

[1] Heat Exchange Institute. Standards for Steam Surface Condensers. 2006. Google Scholar

[2] Zhang C, Sousa A, Venart J. Numerical simulation of different types of steam surface condensers. J Energy Resour-ASME, 1991, 113: 63-70 CrossRef Google Scholar

[3] Zhang C, Sousa A, Venart J. The numerical and experimental study of a power plant condenser. J Heat Trans-T ASME, 1993, 115: 435-445 CrossRef Google Scholar

[4] Zhang C. Numerical modeling using a quasi-3-dimensional procedure for large power plant condensers. J Heat Trans-T ASME, 1994, 116: 180-188 CrossRef Google Scholar

[5] Malin M R. Modelling flow in an experimental marine condenser. Int Commun Heat Mass, 1997, 24: 597-608 CrossRef Google Scholar

[6] Zhang C, Bokil A. A quasi-three-dimensional approach to simulate the two-phase fluid flow and heat transfer in condensers. Int J Heat Mass Tran, 1997, 40: 3537-3546 CrossRef Google Scholar

[7] Sato K, Taniguchi A, Kamada T, et al. New tube arrangement of condenser for power stations. Fluids Therm Eng, 1998, 41: 752-758 Google Scholar

[8] Roy R P, Ratisher M, Gokhale V K. A computational model of a power plant steam condenser. J Energy Resour-ASME, 2001, 123: 81-91 CrossRef Google Scholar

[9] Ramon I S, Gonzalez M P. Numerical study of the performance of a church window tube bundle condenser. Int J Therm Sci, 2001, 40: 195-204 CrossRef Google Scholar

[10] Prieto M M, Suarez I M, Montanes E. Analysis of the thermal performance of a church window steam condenser for different operational conditions using three models. Appl Therm Eng, 2003, 23: 163-178 CrossRef Google Scholar

[11] Guo Z Y, Zhu H Y, Liang X G. Entransy—A physical quantity describing heat transfer ability. Int J Heat Mass Tran, 2007, 50: 2545-2556 CrossRef Google Scholar

[12] Wei S H, Chen L G, Sun F R. “Volume-point” heat conduction constructal optimization with entransy dissipation minimization objective based on rectangular element. Sci China Ser E Tech Sci, 2008, 51: 1283-1295 CrossRef Google Scholar

[13] Xie Z H, Chen L G, Sun F R. Comparative study on constructal optimizations of t-shaped fin based on entransy dissipation rate minimization and maximum thermal resistance minimization. Sci China Tech Sci, 2011, 54: 1249-1258 CrossRef Google Scholar

[14] Meng J A, Liang X G, Li Z X. Field synergy optimization and enhanced heat transfer by multi-longitudinal vortexes flow in tube. Int J Heat Mass Tran, 2005, 48: 3331-3337 CrossRef Google Scholar

[15] Chen Q, Ren J X, Meng J A. Field synergy equation for turbulent heat transfer and its application. Int J Heat Mass Tran, 2007, 50: 5334-5339 CrossRef Google Scholar

[16] Chen Q, Ren J X. Generalized thermal resistance for convective heat transfer and its relation to entransy dissipation. Chin Sci Bull, 2008, 53: 3753-3761 CrossRef Google Scholar

[17] Chen Q, Wang M R, Pan N, et al. Optimization principles for convective heat transfer. Energy, 2009, 34: 1199-1206 CrossRef Google Scholar

[18] Wu J, Liang X G. Application of entransy dissipation extremum principle in radiative heat transfer optimization. Sci China Ser E Tech Sci, 2008, 51: 1306-1314 Google Scholar

[19] Guo J F, Cheng L, Xu M T. Entransy dissipation number and its application to heat exchanger performance evaluation. Chin Sci Bull, 2009, 54: 2708-2713 Google Scholar

[20] Liu X B, Meng J A, Guo Z Y. Entropy generation extremum and entransy dissipation extremum for heat exchanger optimization. Chin Sci Bull, 2009, 54: 943-947 Google Scholar

[21] Xia S J, Chen L G, Sun F R. Optimization for entransy dissipation minimization in heat exchanger. Chin Sci Bull, 2009, 54: 3587-3595 Google Scholar

[22] Qian X D, Li Z X. Analysis of entransy dissipation in heat exchangers. Int J Therm Sci, 2011, 50: 608-614 CrossRef Google Scholar

[23] Qian X D, Li Z, Li Z X. Entransy-dissipation-based thermal resistance analysis of heat exchanger networks. Chin Sci Bull, 2011, 56: 3289-3295 CrossRef Google Scholar

[24] Guo J F, Xu M T, Cheng L. The influence of viscous heating on the entransy in two-fluid heat exchangers. Sci China Tech Sci, 2011, 54: 1267-1274 CrossRef Google Scholar

[25] Guo J F, Xu M T, Cheng L. Principle of equipartition of entransy dissipation for heat exchanger design. Sci China Tech Sci, 2010, 53: 1309-1314 CrossRef Google Scholar

[26] Li X F, Guo J F, Xu M T, et al. Entransy dissipation minimization for optimization of heat exchanger design. Chin Sci Bull, 2011, 56: 2174-2178 CrossRef Google Scholar

[27] Chen Q, Wu J, Wang M R, et al. A comparison of optimization theories for energy conservation in heat exchanger groups. Chin Sci Bull, 2011, 56: 449-454 CrossRef Google Scholar

[28] Chen Q, Ren J X, Guo Z Y. Field synergy analysis and optimization of decontamination ventilation designs. Int J Heat Mass Trans, 2008, 51: 873-881 CrossRef Google Scholar

[29] Chen Q, Meng J A. Field synergy analysis and optimization of the convective mass transfer in photocatalytic oxidation reactors. Int J Heat Mass Tran, 2008, 51: 2863-2870 CrossRef Google Scholar

[30] Chen Q, Ren J X, Guo Z Y. Fluid flow field synergy principle and its application to drag reduction. Chin Sci Bull, 2008, 53: 1768-1772 Google Scholar

[31] 陈群. 对流传递过程的不可逆性及其优化. 博士学位论文. 北京: 清华大学. 2008, Google Scholar

[32] 曾辉. 布管对凝汽器壳侧流动与传热影响的研究及其应用. 博士学位论文. 北京: 清华大学. 2012, Google Scholar

[33] Zeng H, Meng J A, Li Z X. Analysis of condenser shell side pressure drop based on the mechanical energy loss. Chin Sci Bull, 2012, 57: 4718-4725 CrossRef Google Scholar

[34] Meng J A, Zeng H, Li Z X. Analysis of condenser venting rate based on the air mass entransy increases. Chin Sci Bull, 2014, 59: 3283-3291 CrossRef Google Scholar

[35] Meng J A, Zeng H. A kind of bionic double-connected-tree condenser (in Chinese). Chinese Inventive Patent, 2010101970789 [孟继安, 曾辉. 一种仿生双连树形管束式凝汽器. 中国发明专利, 2010101970789]. Google Scholar

[36] Huadian Electric Power Research Institute. Appraisal report of the rebuilt #2 condenser performances of Laicheng Power Plant, Huadian Power International Corportion Limited (in Chinese). 2014 [华电电力科学研究院. 华电国际莱城发电厂2号机组凝汽器改造后性能鉴定试验报告. 2014]. Google Scholar

Click to view Download high-quality image

Figure 1
Bionic double-tree-shaped tube bundle
Click to view Download high-quality image

Figure 2
Flow and heat transfer performances of double-tree-shaped tube bundle condenser. (a) Streamlines; (b) velocity distribution (m s^-1); (c) pressure distribution; (d) air mass fraction distribution; (e) heat transfer coefficient distribution (W m^-2K^-1); (f) heat load distribution (kW m^-2)
Click to view Download high-quality image

Figure 3
(Color online) The rebuilding #2 condenser of Laicheng Power Plant

Table 1 Composition of momentum entransy loss of different tube arrangement condenser

管束布置	G_mon(kW)	$Φ_{F}$ (kW)	$Φ_{P}$ (kW)	$Φ_{U}$ (kW)	$Φ_{μ}$ (kW)	$Φ_{m β}$ (kW)	$\begin{matrix} Φ_{m β} \\ \frac{Φ_{m β}}{E_{m}} \end{matrix}$ (kW)	$\frac{Φ_{m β}}{E_{m}}$
将军帽型	3085	1102	1201	34	517	2856	230	7.4%
双峰型	1119	443	204	16	298	963	157	14.0%
菱型	2559	1188	688	36	433	2346	213	8.3%
卵型	6626	2104	3748	59	264	6177	449	6.8%

Table 2 Percents of the momentum entransy loss of the forontal two/four rows tubes in the total loss for different tube arrangement condensers

管束布置	前2排冷却管面积/总面积(%)	前2排管动量(火积分) 损失/总损失(%)	前4排冷却管面积/总面积(%)	前4排管动量(火积分) 损失/总损失(%)
将军帽型	21.7	41.3	42.4	61.8
双峰型	22.1	61.8	43.6	81.7
菱型	41.6	75.0	50.8	83.7
卵型	59.1	78.4	65.4	83.6

Table 3 Composition of air mass entransy increases of different tube arrangement condensers

管束布置	G_m,a (mg s^-1)	${\dot{G}}_{m,a}$ (mg s^-1)	$Φ_{G,ma}$ (mg s^-1)	${\dot{G}}_{m,a} ? Φ_{G,ma}$ (mg s^-1)	${\dot{G}}_{m,aβ}$ (mg s^-1)	$\frac{{\dot{G}}_{m,aβ}}{G_{m,a}}$
将军帽型	126	2097	1991	106	20	15.8%
双峰型	1046	5509	4529	980	66	6.3%
菱型	35	2293	2265	28	7	19.0%
卵型	721	2730	2013	716	4	0.6%

Table 4 Air mass entransy increases in air cooling region of different tube arrangement condensers

管束布置

空冷区的空气质量(火积分)增(mg s^-1)

全部区域的空气质量(火积分)增(mg s^-1)

将军帽型

234

106

双峰型

990

980

卵型

719

716

Table 5 Performances of 330 MW condensers with different tube arrangements

管束布置	设计工况			给定抽气量
	壳侧压降 (Pa)	抽气量 (kg h^-1)	HEI标准抽气量 (kg h^-1)	凝汽器背压 (kPa)	HEI标准背压 (kPa)
将军帽型	521	1040	98	5.87	4.69
双峰型	165	130		4.91
菱型	428	5265		6.37
卵型	1033	179		4.94
双连树型	176	48		4.68

2

Citations
0

Altmetric
Article metrics

Email
Export

Entransy analysis of tube arrangement effect on condenser performances and its application

Abstract

Funded by

References

2

0

Interesting search

Top 5Related Articles

管束布置	空冷区的空气质量(火积分)增(mg s^-1)	全部区域的空气质量(火积分)增(mg s^-1)
将军帽型	234	106
双峰型	990	980
卵型	719	716