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.

OAHT System Built and Off-Design Performance Analysis

2013 ◽  
Vol 291-294 ◽  
pp. 1640-1647
Author(s):  
Fan Wei ◽  
Shi Jie Zhang ◽  
Yun Han Xiao
Keyword(s):  
Heat Flow ◽  
Flue Gas ◽  
Cooling Water ◽  
Simulation Method ◽  
Recovery Ratio ◽  
Water Recovery ◽  
Design Performance ◽  
Stable Performance ◽  
Open Cycle ◽  
Heat Transformer

Open cycle absorption heat transformer (OAHT) is built and the off-design performance is discussed with simulation method. Results show the COP changes little when parameters various. The COP increases and water recovery ratio decreases as the temperature and flow rate of flue gas or of cooling water increase. With the same heat flow ejecting, the system has more stable performance as the humidity of flue gas changes.

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.

scholarly journals Experimental Study on Water Recovery from Flue Gas Using Macroporous Ceramic Membrane

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 804 ◽  
Author(s):  
Cheng ◽  
Zhang ◽  
Chen
Keyword(s):  
Flow Rate ◽  
Flue Gas ◽  
Heat Recovery ◽  
Gas Flow ◽  
Ceramic Membrane ◽  
Coolant Temperature ◽  
Water Recovery ◽  
Water Coolant ◽  
Gas Flow Rate ◽  
Recycled Water

In this work, a ceramic membrane tube with a pore size of 1 μm was used to conduct experimental research on moisture and waste heat recovery from flue gas. The length, inner/outer diameter, and porosity were 800 mm, 8/12 mm, and 27.2%, respectively. In the experiments, the flue gas, which was artificially prepared, flowed on the shell side of membrane module. The water coolant passed through the membrane counter-currently with the gas. The effects of flue gas flow rate, flue gas temperature, water coolant flux, and water coolant temperature on the membrane recovery performance were analyzed. The results indicated that, upon increasing the flue gas flow rate and its temperature, both the amount of recycled water and the recovered heat increased. The amount of recycled water, recycled water rate, recovered heat, and heat recovery rate all decreased as the water coolant temperature increased. When the water coolant temperature exceeded 30 °C, the amount of recycled water dropped sharply. The maximum amounts of recycled water, recovered heat, and total heat transfer coefficient were 2.93 kg/(m2·h), 3.63 kW/m2, and 224.3 W/(m2·K), respectively.

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

An experimental study on latent heat recovery of exhaust wet flue gas

2002 ◽  
Vol 11 (2) ◽  
pp. 144-147 ◽  
Author(s):  
Li Jia ◽  
Xiaoping Li ◽  
Jindong Sun ◽  
Xiaofeng Peng
Keyword(s):  
Experimental Study ◽  
Latent Heat ◽  
Flue Gas ◽  
Heat Recovery

scholarly journals The effect of the District Heating Return Temperature Reduction on Flue Gas Condenser Efficiency

2020 ◽  
Vol 24 (3) ◽  
pp. 23-38
Author(s):  
Kertu Lepiksaar ◽  
Anna Volkova ◽  
Pavel Ruseljuk ◽  
Andres Siirde
Keyword(s):  
Flue Gas ◽  
Heat Recovery ◽  
Energy Savings ◽  
District Heating ◽  
Primary Energy ◽  
Calculation Model ◽  
Fuel Moisture ◽  
Temperature Reduction ◽  
Boiler Efficiency ◽  
Heating Networks

AbstractThe use of flue gas condensers proved to be effective in increasing boiler efficiency and achieving primary energy savings. The transition to the 4th generation district heating will lead to temperature reduction in district heating networks. The aim of this study is to determine the effects of the reduction in the district heating return temperature on flue gas condenser efficiency. Different DH return temperatures and fuel moisture contents were examined, and a calculation model was created. The results show that a reduction in district heating return temperature can lead to an increase in heat recovery through the flue gas condenser. Primary energy savings were estimated based on the amount of heat recovered.

scholarly journals Experimental Study on a Ceramic Membrane Condenser with Air Medium for Water and Waste Heat Recovery from Flue Gas

Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 701
Author(s):  
Da Teng ◽  
Liansuo An ◽  
Guoqing Shen ◽  
Shiping Zhang ◽  
Heng Zhang
Keyword(s):  
Flue Gas ◽  
Negative Pressure ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Ceramic Membrane ◽  
Waste Heat ◽  
Outlet Temperature ◽  
Water Recovery ◽  
Cooling Medium ◽  
Transfer Characteristics

Ceramic membrane condensers that are used for water and waste heat recovery from flue gas have the dual effects of saving water resources and improving energy efficiency. However, most ceramic membrane condensers use water as the cooling medium, which can obtain a higher water recovery flux, but the waste heat temperature is lower, which is difficult to use. This paper proposes to use the secondary boiler air as the cooling medium, build a ceramic membrane condenser with negative pressure air to recover water and waste heat from the flue gas, and analyze the transfer characteristics of flue gas water and waste heat in the membrane condenser. Based on the experimental results, it is technically feasible for the ceramic membrane condenser to use negative pressure air as the cooling medium. The flue gas temperature has the most obvious influence on the water and heat transfer characteristics. The waste heat recovery is dominated by latent heat of water vapor, accounting for 80% or above. The negative pressure air outlet temperature of the ceramic membrane condenser can reach 50.5 °C, and it is in a supersaturated state. The research content of this article provides a new idea for the water and waste heat recovery from flue gas.

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