Thermal-Hydraulic Behavior and Prediction of Heat Exchanger for Latent Heat Recovery of Exhaust Flue Gas

1999 ◽  
Author(s):  
Masahiro Osakabe
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Flow Rate ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Pressure Loss ◽  
Heat Recovery ◽  
Finned Tubes ◽  
Temperature Distributions ◽  
Inner Diameter

Abstract In order to improve the boiler efficiency, latent heat recovery from the flue gas is very important concept. Three kinds of countercurrent cross-flow heat exchangers, which consist of bare tubes, spirally finned tubes of fin pitch 5 and 10mm, were designed and used for the experiment. The heat exchanger of the bare tubes consists of a staggered bank of 5-4 rows and 50 stages. The length, outer and inner diameter of the bare tube is 482, 27.2 and 23.2mm, respectively. The heat exchangers of finned tubes consist of staggered banks of 3-2 rows, 34 stages for the fin pitch 10mm and 20 stages for the pitch 5mm. The length, outer and inner diameter of the base tube welded with the fins is 482, 34 and 28.8mm, respectively. The thickness and height of the plate fin are 1 and 12mm, respectively. The parametric study varying the flue gas flow rate, feed water temperature and flow rate was conducted. The temperature distributions of water and flue gas in the heat exchanger were measured with sheath K-type thermocouples of 1.6 mm in diameter. The pressure loss and the total amount of condensate generated in the heat exchanger were also measured. Based on the previous basic studies, a prediction method for the heat exchanger was proposed. In the prediction, the flue gas was treated as a mixture of CO2, CO, O2, N2 and H2O, and the one-dimensional heat and mass balance calculation along the flow direction of flue gas was conducted. The heat and mass transfer on tubes was evaluated with a simple analogy correlation. For the finned tubes, the fin efficiency at the condensing region was calculated with a semi-empirical correlation obtained in the previous basic study. The effect of condensate film on the tubes was considered to be negligibly small for the heat transfer and pressure loss calculation. The experimental results for the temperature distributions of water and flue gas in the test heat exchangers with bare and finned tubes agreed well with the prediction.

The latent heat recovery from boiler exhaust flue gas using shell and corrugated tube heat exchanger: A numerical study

Heat Transfer ◽  
2020 ◽  
Vol 49 (6) ◽  
pp. 3797-3815 ◽  
Author(s):  
Sharare Mohammadi ◽  
Seyed Soheil Mousavi Ajarostaghi ◽  
Mohsen Pourfallah
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Flue Gas ◽  
Heat Recovery ◽  
Numerical Study ◽  
Tube Heat Exchanger ◽  
Corrugated Tube

Pilot-scale study on water and latent heat recovery from flue gas using fluorine plastic heat exchangers

2017 ◽  
Vol 161 ◽  
pp. 1416-1422 ◽  
Author(s):  
Yingying Xiong ◽  
Houzhang Tan ◽  
Yibin Wang ◽  
Weigang Xu ◽  
Hrvoje Mikulčić ◽  
...  
Keyword(s):  
Latent Heat ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Pilot Scale

Effect of Header on Latent Heat Recovery Heat Exchanger

2011 ◽  
Author(s):  
Masahiro Osakabe
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Recovery Rate ◽  
Pressure Loss ◽  
Heat Recovery ◽  
Reduction Rate ◽  
Small Diameter ◽  
Prediction Method ◽  
Exhaust Gas ◽  
Water Side

The most part of energy losses in heat & power system is due to the heat released by the exhaust gas to atmosphere. The exhaust gas consists of non-condensable gas and steam with sensible and latent heat. As a lot of latent heat is included in the exhaust gas, its recovery is very important to improve the system efficiency. Based on the previous basic studies, a thermal hydraulic prediction method for latent heat recovery exchangers was proposed. Two kinds of compact heat exchanger with staggered banks of large and small diameter tubes were designed and fabricated based on the prediction method. In the calculations varying the various parameters, approximately the same heat recovery rate was obtained with both the heat exchangers. The more compactness was obtained with the small tubes at a desired heat recovery rate. The pressure loss in gas side was slightly smaller and that in water side was significantly larger incase of the small tube. By adapting the single header instead of conventional multi header, the pressure loss in the water side could be significantly reduced but the reduction rate of heat recovery was only between 40 to 10%.

Design Considerations and Heat Transfer Enhancement of CFB Heat Exchangers for Flue Gas Heat Recovery

2005 ◽  
Author(s):  
Yong-Du Jun ◽  
Kum-Bae Lee ◽  
Seok-Bo Ko ◽  
Sheikh Zahidul Islam
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Heat Transfer Performance ◽  
Fluid Composition ◽  
Generation Model ◽  
Transfer Performance

Now-a-day’s energy recovery process in the industry is a common practice for improving the production process while major concern goes to environment. The performance of the heat exchangers, used for the purpose of recovering energy, decreases continuously with time due to fouling depending on surface temperature, surface condition, construction material, fluid velocity, flow geometry and fluid composition. To overcome the fouling of fly ash on the heat transfer surface and erosion and periodical cleaning which are the major drawbacks in conventional heat exchangers for flue gas heat recovery, a no-distributor-circulating-fluidized-bed (NDCFB) heat exchanger with automatic particle controlling is devised. One of the main advantages of this model is the reduced pressure drop through the entire heat exchanger system, while increasing heat transfer performance. The research started with a single riser system with multiple down comers and multi-riser system is also studied. The heat transfer performance and pressure drop have been evaluated through experiments for these gas-to-water lab scale heat exchanger systems. However, due to the operational complexity, these two models are not readily applicable to real applications. As a derivation of the previous studies regarding the no-distributor CFB heat exchangers, third generation model of the heat exchanger is now under investigation.

scholarly journals High Performance Heat Exchanger for Latent Heat Recovery from Flue Gas

2013 ◽  
Vol 79 (803) ◽  
pp. 1363-1374 ◽  
Author(s):  
Junpei YAMASHITA ◽  
Yoshio UTAKA ◽  
Masakazu KOBAYASHI ◽  
Yasuhiro SANO
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Flue Gas ◽  
Heat Recovery ◽  
High Performance

Latent Heat Recovery and Performance Studies for an Open Cycle Absorption Heat Transformer

2008 ◽  
Author(s):  
Fan Wei ◽  
Yunhan Xiao ◽  
Shijie Zhang
Keyword(s):  
Latent Heat ◽  
Flow Rate ◽  
Flue Gas ◽  
Heat Recovery ◽  
District Heating ◽  
Solution Concentration ◽  
High Flow ◽  
Water Recovery ◽  
Open Cycle ◽  
Heat Transformer

Latent heat recovery from the flue gas has received considerable attention due to its large quantities especially in gas boilers or humid gas turbine cycles (such as HAT cycle). Furthermore, the cost of water consumption can be reduced in gas turbine systems by water recovery along with latent heat recovery. In this paper, an open cycle absorption heat transformer (OAHT) is developed for latent heat and water recovery from flue gas. The exhaust gas is used as the heat source to boil the weak solution and water-calcium chloride as the desiccant to absorb water. The discharged heat from absorber can be used for district heating. Comparing with the conventional condensation method, the heat and water recovery from the OAHT is analyzed by employing the flow sheet simulation method. The results show that under the same working condition, the amount of recovered heat in the OAHT is 1.6 times that in the condensation method, the latent heat is 2.8 times; the amount of water recovery increases by 7.3 fold. The performance and the parametric analysis of the OAHT are also developed. The Coefficient of Performance (COP) of the system is 0.65. The discharged heat from the absorber is 4.807kW at the temperature of 50°C which can be used for district heating. Parametric analysis show that COP will increase with high gas temperature and humidity, high cooling water temperature and flow rate, high strong solution concentration and high flow rate of working fluid; while high flow rate of gas and weak solution concentration will make COP decrease. The advantages of the OAHT are demonstrated in the water and latent heat recovery. Comparing with the closed cycle absorption heat transformer, the OAHT has more advantages because of the relative similar COP and the simple configuration which can reduce the system cost.

Latent heat recovery from actual flue gas

2002 ◽  
Author(s):  
Masahiro Osakabe ◽  
Sachiyo Horiki ◽  
Tsugue Itoh ◽  
Ikuya Haze
Keyword(s):  
Latent Heat ◽  
Flue Gas ◽  
Heat Recovery ◽  
Actual Flue Gas
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