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Waste Heat Recovery
Published in Harry Taplin, Boiler Plant and Distribution System Optimization Manual, 2021
Based on a number of general assessments considering all facts involved in economic benefits, engineering criteria, installing and operating waste heat recovery systems; three primary systems have evolved as being very good prospects for waste heat recovery. The waste heat recovery systems which showed the most promise and applicability are: The conventional economizerThe indirect-contact condensing heat exchangerDirect contact flue gas condensation heat recovery
Modular Systems for Energy Usage in District Heating
Published in Yatish T. Shah, Modular Systems for Energy Usage Management, 2020
For Sala-Heby Energi AB, FVB provided the initial concept design analysis and detail design for the central heating plant, distribution piping system, system hydraulic modeling, and building connections. Based on FVB’s feasibility study, Sala-Heby Energi constructed a biomass-fueled CHP plant. The biomass CHP plant produces 10 MWe and 22 MWth. From 1998 to the present FVB continues to assist Sala-Heby Energi in expanding their system and connecting new customers. FVB has also prepared the detail design and tender documents for an additional flue gas condensation plant. FVB continues to provide support for combustion optimization, control systems, and other miscellaneous system enhancements.
4E-analysis of sustainable hybrid tri-generation system
Published in Anoop Kumar Shukla, Onkar Singh, Meeta Sharma, Rakesh Kumar Phanden, J. Paulo Davim, Hybrid Power Cycle Arrangements for Lower Emissions, 2022
Meisam Sadi, Ahmad Arabkoohsar
The hybrid system shows that the hot water is supposed to be prepared in a heat exchanger connected to the condenser and flue gas condensation of the WI power plant. As we know this equipment is installed once and is used during the period of the project which is considered 20 years for this case. Consequently, there would be three types of expenses during this project; expenses related to the installation at the first year of the project, the expenses related to the heat loss through the pipes, and finally the electricity cost of pumping during the project period. To select the best feeding pipeline size, all these expenses should be investigated during the project time. For this reason, for different sizes of diameter, these expenses are represented in Figure 10.9. When the pipeline diameter changes, the first point is that the cost of the pipeline changes. Then this change would affect the electricity consumption. When the diameter changes, the velocity of the working fluid inside of the pipeline varies. According to the velocity limit of the district heating pipeline, a decrease in diameter could not happen as much as possible. Thus, due to these controversial effects, the figure shows that for a diameter of 50 cm, the minimum pipeline cost will occur. It is worth mentioning that when the diameter decreases, the velocity of working fluid inside of the pipe exceeds its limit, thus the number of pipelines should be increased, which means the huge extra expense of pipelines and installation. This figure shows that the cost of heat loss occurring through the pipeline wall minimizes when the diameter is 50 cm. When the diameter is larger, it means a higher surface for heat transfer and consequently higher heat loss. For smaller diameter, it should be mentioned that the number of pipelines causes the surface of heat transfer to increase, and thus the optimum diameter from the heat loss point of view would be considered 50 cm. The third factor affecting the expenses of the project is the amount of electricity used for pumping. This parameter decreases when the diameter increases because the friction factor of the pipeline is a function of diameter and it reduces when diameter increases. However, pumping expenses are smaller in comparison with the two other expenses. By considering all three factors, the total cost of pipeline experiences a minimum value when the diameter is 50 cm.
Investigation of the condensation heat-transfer between the wet air and 3-D finned-tube heat exchanger surface with different anti-corrosion coatings
Published in Experimental Heat Transfer, 2022
Yixin Zhang, Suilin Wang, Wei Zhang, Yudong Ding, Min Cheng, Lianbo Mu, Xudong Zhao
The experimental setup is composed of fuel combustion, water supply, flue-gas heat exchanger, flue-gas condensation heat-transfer section, data acquisition, and controlling system. The sample natural gas and air were pre-mixed and flowed into the combustor 5. The combustion product first entered the first-stage heat exchanger 6 and its sensible heat was transferred to subcooled water. The outlet temperature of flue gas was controlled by the adjustable mass flowrate of cooling water. In the second-stage heat exchanger 7 (marked by the red dotted-line box), both the sensible and latent heat of flue gas were transferred to the cooling water. The water vapor condensed from the flue gas was collected through the tray 8 and beaker 9 at the bottom of flue duct. The water tank was used for the stabilization of the flow rate of cooling water. The condensate pH was measured by the pH electrode. The schematic diagram and photograph of the experimental setup are shown in Figures 1 and 2, respectively.
The numerical study of the thermal performance of a condensing gas-water heater
Published in Numerical Heat Transfer, Part A: Applications, 2018
Weixue Cao, Fengguo Liu, Xue-Yi You
When the heat exchanger works through different seasons, gas flow levels differ and amounts of flue gas generated by combustion also vary. In the winter, the flue gas flow rate is greater than it is in the summer, resulting in different water temperatures within the water heater. Temperature distributions measured at the center of the Y axis are shown in Figure 10c, d. From the two working conditions, it is evident that effective heat transfer processes occurred between the flue gas and the fin and water wall surfaces. The temperature of the flue gas dropped rapidly. The non-uniformity of the temperature is shown at the outlet of the flue gas and mainly due to the condensation of water vapor in the flue gas. When the flue gas temperature reaches 42–58 °C (α = 1), vapor in the flue gas condenses. For the winter conditions shown in Figure 10a, the temperature of the flue gas drops to approximately 450–600 °C in the HTZ, and under summer conditions illustrated in Figure 10b, temperatures drop to approximately 400–550 °C in the HTZ. At the outlet of the flue gas, condensation occurs in both the winter and summer. In the LTZ, flue gas flows through the pin fin and transfers heat to the fin and water wall. In the winter flue gas temperatures drop to 30–60 °C, and in the summer they drop to 20–50 °C.
Development of new correlations for heat transfer and friction loss of solid ring with combined square wing twisted tape inserts heat exchanger tube
Published in Experimental Heat Transfer, 2019
Ravi Datt, Mangal Singh Bhist, Alok Darshan Kotiyal, Rajesh Maithani, Anil Kumar
Zeynali and Abolfazli [20] presented the outcomes of an experimental and numerical analysis of TT inserts on wet flue gas condensation in a horizontal HET. The experiment was conducted with four dissimilar TT inserts under dissimilar ranges of combustion excess air. Hong et al. [21] experimentally examined the efficiency factor of turbulent flow in HETs by using overlapped multiple TTs with offset large/small combinations. Piriyarungrod et al. [22] carried out an experimental investigation of HETs with tapered TT inserts on heat transfer enhancement using air as a working fluid. They observed that the heat transfer augmentation and friction flow improved on reducing the taper angle and twist ratio.