Numerical Optimization of a Piece-Wise Conical Contraction Zone of a High-Pressure Wind Tunnel

2015 ◽  
Author(s):  
Karsten Hasselmann ◽  
Felix Reinker ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig
Keyword(s):  
Fluid Dynamics ◽  
Wind Tunnel ◽  
Low Temperature ◽  
Flow Field ◽  
Waste Heat ◽  
Design Guidelines ◽  
Optimal Shape ◽  
Geometrical Approach ◽  
Separation Criterion ◽  
The Ideal

The Organic Rankine Cycle (ORC) offers a great potential for recovering waste heat and using low-temperature sources for power generation. However, the ORC thermal efficiency is limited by the relatively low temperature level, and, therefore, designing ORC components with high efficiencies and minimized losses is of major importance. Such an approach requires the use of a specially designed closed cascade wind tunnel. This contribution presents the design of the contraction zone shape. The ideal shape can be defined by a sixth order polynomial yielding a smooth curve for the nozzle profile. Due to pressure vessel costs, it is not possible to realize the whole contraction zone as one piece for this wind tunnel. Instead, a piece-wise conical design approach is chosen. Classical nozzle design guidelines do not offer an analytical solution to this flow problem. Therefore, computational fluid dynamics (CFD) in combination with Stratford’s separation criterion is used for an optimization study of a piece-wise conical contraction zone. Different combination of numbers of components, length, and inflection points are investigated. The optimization minimizes the flow deviation of the chosen profile to the optimal shape in two steps: a geometrical approach to the optimal shape and an optimization of the flow field within the contraction zone. The geometrical optimization yields a profile with minor deviation to the ideal shape. For the flow field optimization, a CFD analysis is used to minimize flow separations at the break points between the single conical pieces, especially those at the far end of the contraction zone. All shapes are investigated by Stratford’s separation criterion, which is adopted to conical pieces. The presented analysis indicates that the flow field optimization yields a much better approach for the fluid dynamics of the wind tunnel than the geometrical approach.

Numerical Study of Multistage Serial and Parallel Configurations of Thermoacoustic Engines

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
Adnan Poshtkouhian Badi ◽  
Hamid Beheshti
Keyword(s):  
Fluid Dynamics ◽  
Low Temperature ◽  
Cfd Simulation ◽  
Waste Heat ◽  
Numerical Study ◽  
Initial Pressure ◽  
Heat Pumps ◽  
Published Data ◽  
Pressure Amplitude ◽  
Thermoacoustic Engines

The focus of this study is on serial and parallel configurations of a multistage thermoacoustic engines (TAE). Thermoacoustics integrates fluid dynamics, thermodynamics, and acoustics to explain the interactions existing between heat and sound. Considerable amounts of waste heat are released to the environment in everyday industrial processes. This waste heat cannot be reused due to its low temperature. One way for reusing some of this waste heat is to employ a thermoacoustic heat pump. TAEs can be driven by waste heat and are capable of supplying the power to drive the thermoacoustic heat pumps. However, due to the low temperature of this waste heat, single-stage TAEs cannot provide the required temperature lifts. Multistage TAEs are advantageous because they can provide sufficient temperature lifts. In this study, a computational fluid dynamics (CFD) simulation is carried out to understand the conversion process of heat to sound and study the nonlinear conjugation of unsteady heat release and acoustic disturbances. The two main parameters evaluated in this simulation are the initial pressure disturbance and the stack's temperature gradient. Their effects on actuating limit cycle oscillations are examined in a 2D numerical model. The numerical simulation results indicate that the pressure amplitude varies through alteration made in these mentioned parameters. The present numerical results are validated by previously published data.

Computational fluid dynamics simulation of the supersonic steam ejector. Part 1: Comparative study of different equations of state

2011 ◽  
Vol 226 (3) ◽  
pp. 709-714 ◽  
Author(s):  
H T Zheng ◽  
L Cai ◽  
Y J Li ◽  
Z M Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Equations Of State ◽  
Ideal Gas ◽  
Dynamics Simulation ◽  
Real Gas ◽  
Steam Ejector ◽  
Ideal Gas Model ◽  
The Ideal

The aim of this study is to investigate the use of computational fluid dynamics in predicting the performance and geometry of the optimal design of a steam ejector used in a steam turbine. Many scholars have analysed the steam ejector using the ideal gas model, which lacks accuracy in terms of calculating the flow field of the ejector. This study is reported in a series of two papers. The first part covers the validation of CFX 11.0 results using different equations of state (EOS) on the converging–diverging nozzle flow field carried out with the experimental value. The IAPWS IF97 real gas model works well with the experimental value. The flow field of the ejector was analysed using different EOS after grid-dependent learning. The results show that the performance of the ejector was underestimated under the ideal gas model; the entrainment ratio was 20–40 per cent lower than when using the real gas model. The effect of the optimal geometrical design and operating conditions will be discussed in Part 2.

Efficiency and Economy Research of a Tunnel Kiln's Flue Gas Heat Exchanger

2013 ◽  
Vol 834-836 ◽  
pp. 1967-1971
Author(s):  
Jie Li ◽  
Yong Hong Zhu ◽  
Sun Jian
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Temperature Field ◽  
Heat Exchanger ◽  
Flow Field ◽  
Flue Gas ◽  
Energy Savings ◽  
Waste Heat ◽  
Calculation Results ◽  
Recycle And Reuse

In order to obtain efficiency and economy of a ceramic tunnel kiln’s flue gas heat exchanger, firstly, the exchanger’s sizes and thermal parameters on operative conditions were measured. Secondly, flow field and temperature field in the operative exchanger were numerically simulated by using FLUENT, a computational fluid dynamics soft ware. Finally, on base of the simulation, the exchanger’s efficiency and economy were calculated. The calculation results are listed as the following: (1) Energy savings in per unit time for utilizing the heat exchanger to recycle and reuse the flue gas’s waste heat is 112.2kW. (2) Efficiency of the heat exchanger equals 77%.

Thermodynamics and Fluid Mechanics of a Closed Blade Cascade Wind Tunnel for Organic Vapors

2015 ◽  
Vol 138 (5) ◽  
Author(s):  
Felix Reinker ◽  
Karsten Hasselmann ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig
Keyword(s):  
Wind Tunnel ◽  
Low Temperature ◽  
Gas Turbines ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Settling Chamber ◽  
Analysis Tool ◽  
Organic Vapors

The organic Rankine cycle (ORC) offers great potential for waste heat recovery and use of low-temperature sources for power generation. However, the ORC thermal efficiency is limited by the relatively low-temperature level, and it is, therefore, of major importance to design ORC components with high efficiencies and minimized losses. The use of organic fluids creates new challenges for turbine design, due to dense gas behavior and the low speed of sound. The design and performance predictions for steam and gas turbines have been initially based on measurements and numerical simulations of flow through two-dimensional cascades of blades. In case of ORC turbines and related fluids, such an approach requires the use of a specially designed closed cascade wind tunnel. In this contribution the design and process engineering of a continuous running wind tunnel for organic vapors is presented. The wind tunnel can be operated with heavy weight organic working fluids within a broad range of pressure and temperature levels. For this reason, the use of classical design rules for atmospheric wind tunnels is limited. The thermodynamic cycle process in the closed wind tunnel is modeled, and simulated by means of a professional power plant analysis tool, including a database for the ORC fluid properties under consideration. The wind tunnel is designed as a pressure vessel system and this leads to significant challenges particular for the employed wide angle diffuser, settling chamber, and nozzle. Detailed computational fluid dynamics (CFD) was performed in order to optimize the important wind tunnel sections.

Thermodynamics and Fluid Mechanics of a Closed Blade Cascade Wind Tunnel for Organic Vapors

2015 ◽  
Author(s):  
Felix Reinker ◽  
Karsten Hasselmann ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig
Keyword(s):  
Wind Tunnel ◽  
Low Temperature ◽  
Gas Turbines ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Settling Chamber ◽  
Analysis Tool ◽  
Organic Vapors

The Organic Rankine Cycle (ORC) offers great potential for waste heat recovery and use of low-temperature sources for power generation. However, the ORC thermal efficiency is limited by the relatively low temperature level, and it is, therefore, of major importance to design ORC components with high efficiencies and minimized losses. The use of organic fluids creates new challenges for turbine design, due to dense gas behavior and the low speed of sound. The design and performance predictions for steam and gas turbines have been initially based on measurements and numerical simulations of flow through two-dimensional cascades of blades. In case of ORC turbines and related fluids, such an approach requires the use of a specially designed closed cascade wind tunnel. In this contribution the design and process engineering of a continuous running wind tunnel for organic vapors is presented. The wind tunnel can be operated with heavy weight organic working fluids within a broad range of pressure and temperature levels. For this reason, the use of classical design rules for atmospheric wind tunnels is limited. The thermodynamic cycle process in the closed wind tunnel is modeled and simulated by means of a professional power plant analysis tool, including a database for the ORC fluid properties under consideration. The wind tunnel is designed as a pressure vessel system and this leads to significant challenges particular for the employed wide angle diffuser, settling chamber, and nozzle. Detailed computational fluid dynamics analyses (CFD) were performed in order to optimize the important wind tunnel sections.

Design of Small-Scale Radial Inflow Turbine Integrated into Organic Rankine Cycle

2012 ◽  
Vol 524-527 ◽  
pp. 3907-3913
Author(s):  
Hui Wang ◽  
Xin Ling Ma ◽  
Xin Li Wei
Keyword(s):  
Low Temperature ◽  
Flow Field ◽  
Simple Structure ◽  
High Efficiency ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
3D Models ◽  
Small Scale ◽  
Radial Inflow Turbine

Organic Rankine Cycle (ORC) is dramatically suitable for low temperature waste-heat generation. The small-scale radial inflow turbine is introduced to integrate into the ORC characterized by simple structure, low parts count, high efficiency, especially getting high efficiency under the condition of smaller flow. This turbine is comprised of four main parts named by the volute, the nozzle (stator), the impeller (rotor), and the diffuser respectively. This paper introduces how to design and model the parts in detail, discusses modeling skills and shares experience. The structure of the volute and impeller is so complicated that parts are not easy to model. These 3D models can directly import to both ANSYS and FLUENT to analysis the flow field in order to achieve the optimize parameters.

scholarly journals Local Heating Networks with Waste Heat Utilization: Low or Medium Temperature Supply?

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 954 ◽  
Author(s):  
Hanne Kauko ◽  
Daniel Rohde ◽  
Armin Hafner
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Urban Areas ◽  
Waste Heat ◽  
Local Heating ◽  
District Heating ◽  
Heat Pumps ◽  
Hot Water ◽  
Local Network ◽  
Medium Temperature

District heating enables an economical use of energy sources that would otherwise be wasted to cover the heating demands of buildings in urban areas. For efficient utilization of local waste heat and renewable heat sources, low distribution temperatures are of crucial importance. This study evaluates a local heating network being planned for a new building area in Trondheim, Norway, with waste heat available from a nearby ice skating rink. Two alternative supply temperature levels have been evaluated with dynamic simulations: low temperature (40 °C), with direct utilization of waste heat and decentralized domestic hot water (DHW) production using heat pumps; and medium temperature (70 °C), applying a centralized heat pump to lift the temperature of the waste heat. The local network will be connected to the primary district heating network to cover the remaining heat demand. The simulation results show that with a medium temperature supply, the peak power demand is up to three times higher than with a low temperature supply. This results from the fact that the centralized heat pump lifts the temperature for the entire network, including space and DHW heating demands. With a low temperature supply, heat pumps are applied only for DHW production, which enables a low and even electricity demand. On the other hand, with a low temperature supply, the district heating demand is high in the wintertime, in particular if the waste heat temperature is low. The choice of a suitable supply temperature level for a local heating network is hence strongly dependent on the temperature of the available waste heat, but also on the costs and emissions related to the production of district heating and electricity in the different seasons.

scholarly journals RELaTED Project: New Developments on Ultra-Low Temperature District Heating Networks

Proceedings ◽  
2020 ◽  
Vol 65 (1) ◽  
pp. 25
Author(s):  
Antonio Garrido Marijuan ◽  
Roberto Garay ◽  
Mikel Lumbreras ◽  
Víctor Sánchez ◽  
Olga Macias ◽  
...  
Keyword(s):  
Low Temperature ◽  
High Performance ◽  
Waste Heat ◽  
District Heating ◽  
Hot Water ◽  
Thermal Systems ◽  
Heating Source ◽  
Wide Range ◽  
Thermal Sources ◽  
Heating Networks

District heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning district heating-connected reversible heat pump systems that allow to reach adequate thermal levels for domestic hot water as well as the use of the network for district cooling with high performance. These developments will be demonstrated in four locations: Estonia, Serbia, Denmark, and Spain.

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