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%.

Prediction and Performance of Compact Latent Heat Recovery Heat Exchanger With Small Diameter Tubes

2007 ◽  
Author(s):  
Masahiro Osakabe
Keyword(s):  
Heat Exchanger ◽  
Power System ◽  
Latent Heat ◽  
Heat Recovery ◽  
Small Diameter ◽  
Cooling Water ◽  
Prediction Method ◽  
Outer Diameter ◽  
Exhaust Gas ◽  
And Performance

The most part of energy losses in power system such as fuel cells 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 power system efficiency. Based on the previous basic studies, a thermal hydraulic prediction method for latent heat recovery exchangers was proposed. For the condensation of steam on heat transfer tubes, the modified Sherwood number taking account of the mass absorption effect on the wall was used. Two kinds of compact heat exchanger with staggered banks of bare tubes of 10.5 or 4mm in outer diameter was designed with the prediction method. The more compactness was obtained with the smaller tubes at a designed heat recovery. The thermal hydraulic behavior in the compact heat exchangers was experimentally studied with air-steam mixture gas. In the parametric experiments varying the steam mass concentration, the temperature distributions of cooling water and mixture gas were measured. The experimental results agreed well with the prediction proposed in this study and the more compactness with the smaller tubes was proved.

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.

EFFECT OF CONDENSATION ON THE EFFICIENCY OF HEAT RECOVERY VENTILATORS FOR BROILER HOUSES

2013 ◽  
Vol 21 (02) ◽  
pp. 1350009 ◽  
Author(s):  
HWATAIK HAN ◽  
SANG-HOON NAM ◽  
GEON-SOO HAN
Keyword(s):  
Heat Exchanger ◽  
Relative Humidity ◽  
Latent Heat ◽  
Heat Recovery ◽  
Harsh Environments ◽  
Sensible Heat ◽  
Outdoor Temperature ◽  
Toxic Gases ◽  
Temperature Efficiency ◽  
Plate Type

This study experimentally investigates the effect of internal condensation on the performance of a heat recovery ventilator. Experiments were performed using a plate-type sensible heat exchanger element that was designed for very humid and dusty environments such as chicken broiler houses. The results of these experiments show that the temperature efficiency considering condensation is always greater than that without considering latent heat. As outdoor temperature decreases or indoor relative humidity increases, temperature efficiency increases owing to an increase in the rate of condensation. The present polypropylene-based sensible heat exchanger element could be a solution for harsh environments because it can discharge condensate water by gravity and is resistant to moisture and other toxic gases.

scholarly journals Investigation of a Heat Pipe Heat Exchanger Integrated with a Water Spray for the Heat Recovery from Boil Exhaust Gas

2014 ◽  
Vol 61 ◽  
pp. 2141-2144 ◽  
Author(s):  
Ye Yuan ◽  
Yiji Lu ◽  
Huashan Bao ◽  
Yaodong Wang ◽  
Wen Wang ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Recovery ◽  
Exhaust Gas ◽  
Water Spray ◽  
Pipe Heat

The heat transfer and pressure loss characteristics of a heat exchanger for recovering latent heat (the heat transfer and pressure loss characteristics of the heat exchanger with wing fin)

2007 ◽  
Vol 36 (4) ◽  
pp. 215-229
Author(s):  
Kiyoshi Kawaguchi ◽  
Kenichi Okui ◽  
Takahiro Shimoura ◽  
Takaki Ohkouchi ◽  
Hiroyuki Osakabe ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Latent Heat ◽  
Pressure Loss

scholarly journals Effects of the exhaust gas heat recovery system with a plate heat exchanger on the warm-up performance characteristics of the gasoline engine

2018 ◽  
Vol 7 (2.12) ◽  
pp. 136
Author(s):  
Chan JungKim ◽  
Sank Wook-Han ◽  
Ki Hyun Kim ◽  
Moo Yeon Lee ◽  
Gee Soo Lee
Keyword(s):  
Heat Exchanger ◽  
Fuel Economy ◽  
Heat Recovery ◽  
Exhaust System ◽  
Plate Heat Exchanger ◽  
Exhaust Gas ◽  
Warm Up ◽  
Plate Heat ◽  
Recovery System ◽  
Heat Recovery System

Background/Objectives: To meet the regulations for the fuel economy, an EHRS (Exhaust gas Heat Recovery System, which was installed within the vehicle exhaust system and recovered the heat from the exhaust gas, were needed. The EHRS enabled the engine to achieve the fast warm-up performance for reducing friction loss during the cold start.The objective of this paper was to investigate the effects of the design parameters of the EHRS with a plate heat exchanger on the warm-up performance of a gasoline engine.Methods/Statistical analysis: The EHRS with the plate heat exchanger was manufactured and installed behind the catalyst in the exhaust system of the gasoline direct injection engine. The experimental study and multi-disciplinary analysis were carried out to investigate the effects of the EHRS on the warm-up performance of the engine, such as the coolant temperature, the exhaust gas temperature and the recovery heat at idle condition and the step-load condition.Findings: Because the recovery of heat was about 1. 7 kW at idle condition, the effect of the EHRS on the warm-up performance was negligible. However, due to 17.2 kW of the recovery of heat at the stepload condition of T=140 Nm at N=2,400 rpm, the EHRS enabled to shorten the warm-up time by 548 s comparison that of the base engine.Improvements/Applications: The fuel economy will be expected to be improved through an EHRS, which provides the improved combustion in the warm-up phase and a decrease in friction loss.  

Remote Measurement and Heat Demand Control of CHP System With Heat Storage at Sapporo City University

2010 ◽  
Author(s):  
Osamu Kurata ◽  
Norihiko Iki ◽  
Takayuki Matsunuma ◽  
Tetsuhiko Maeda ◽  
Satoshi Hirano ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Heat Supply ◽  
Heat Storage ◽  
Hot Water ◽  
Exhaust Gas ◽  
Latent Heat Storage ◽  
Boiler Water ◽  
Heat Demand ◽  
Partial Load

Combined heat and power (CHP) systems are widely used to prevent global warming and reduce energy costs. Both high efficiency of the elements and good coordination of the systems are considered as the points to solve. A microturbine CHP with a latent heat storage system was demonstrated at Sapporo City University. The heat exchanger of the CHP and an economizer were located in parallel downstream a bypass-dumper of the exhaust gas. The latent heat storage tank was located downstream the economizer. The bypass-dumper released exhaust gas when the boiler water in the heat exchanger exceeded 90°C. It is very important to use the heat supply of hot water as much as possible. At Sapporo City University, the winter term heat demand from 6pm to 7pm was somewhat smaller than that from 8am to 6pm. We tested a partial load from 6pm to 7pm to observe how it would respond to the heat demand. The heat supply from the microturbine CHP from 6pm to 7pm was shown to be controllable with heat storage. The heat supply from the microturbine CHP at the lowest power was larger than the heat demand so without the heat storage it was uncontrollable.

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