A response to industrial maturity and energetic issues: a possible solution based on constructal law

Trancossi, Michele

doi:10.1007/s12544-014-0150-4

Cited by 11 publications

(11 citation statements)

References 37 publications

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“…(18), (19), (23), (29) and (30), and writing that for a channel between parallel plates the friction factor is f ¼ 24=Re D h . The inequality (50) becomes…”

Section: Discussionmentioning

confidence: 99%

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Entrance-length dendritic plate heat exchangers

Bejan

Alalaimi

Sabau

et al. 2017

International Journal of Heat and Mass Transfer

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a b s t r a c tHere we explore the idea that the highest heat transfer rate between two fluids in a given volume is achieved when plate channel lengths are given by the thermal entrance length, i.e., when the thermal boundary layers meet at the exit of each channel. The overall design can be thought of an elemental construct of a dendritic heat exchanger, which consists of two tree-shaped streams arranged in cross flow. Every channel is as long as the thermal entrance length of the developing flow that resides in that channel. The results indicate that the overall design will change with the total volume and total number of channels. We found that the lengths of the surfaces swept in cross flow would have to decrease sizably as number of channels increases, while exhibiting mild decreases as total volume increases. The aspect ratio of each surface swept by fluid in cross flow should be approximately square, independent of total number of channels and volume. We also found that the minimum pumping power decreases sensibly as the total number of channels and the volume increase. The maximized heat transfer rate per unit volume increases sharply as the total volume decreases, in agreement with the natural evolution toward miniaturization in technology.

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“…(18), (19), (23), (29) and (30), and writing that for a channel between parallel plates the friction factor is f ¼ 24=Re D h . The inequality (50) becomes…”

Section: Discussionmentioning

confidence: 99%

“…Advances are published regularly for heat exchangers [4][5][6][7][8][9][10][11][12][13], fuel cells [14], fluid networks [15][16][17][18][19][20], steam generators [21,22], fluid channels [23][24][25][26][27], energy storage [28], transportation [29][30][31][32], power generation [33][34][35][36][37], and management [38].…”

Section: Technology Evolutionmentioning

confidence: 99%

Entrance-length dendritic plate heat exchangers

Bejan

Alalaimi

Sabau

et al. 2017

International Journal of Heat and Mass Transfer

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“…The design method is derived from the optimization of the equations of motions such as in Trancossi et al [18]. This method is an improvement of second principle analysis [19] according to the EMIPS method [20] as adapted by Trancossi [21,22]. It is then a method defined on the flight mechanics equations and energy equations of the system, to define a preliminary optimal configuration that can be then designed and tested.…”

Section: Definition Of the Propulsion System For A Spherical Objectmentioning

confidence: 99%

“…The comparison has been produced according to equation (10) that present the formulation of exergy dissipations according EMIPS model [19] and revised by Trancossi [20,21].…”

Section: Preliminary Benchmark Casementioning

confidence: 99%

Control, Propulsion and Energy Assessment of a Spherical UAS for Low Speed Operations

Bandycki

Trancossi

Páscoa

2017

SAE Technical Paper Series

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This paper presents a comparison between different hypotheses of propulsion of a spherical UAS. Different architectures have been analyzed assessing their specific aerodynamic, energetic, and flight mechanics features. The comparison has been performed assuming the robustness of flight control in different wind conditions, defining for each the specific operative ranges, mission profiles, and energy assessment. An effective energy assessment and comparison against a commercial UAS has been produced. Even if the paper considers a preliminary simplified configuration, it demonstrates clearly to be competitive against traditional quadcopters in a predefined reference mission.

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“…The method allows evaluating cumulative exergy consumption also introducing an effective differentiation between non-renewable and renewable resource inputs according to Gong and Wall [8]. Trancossi [9][10] has modified the model by introducing an effective distinction of the energy needs for moving the vehicle and moving the payload. He does not consider the vehicle as a necessity, but he seeks by this approach to identify how the vehicle can be improved minimize its energy consumption.…”

Section: Energy Balancementioning

confidence: 99%

A New Propelled Wing Aircraft Configuration

Trancossi

Stewart

Páscoa

2016

Volume 1: Advances in Aerospace Technology

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This paper investigates by an energetic approach possible new configurations of aircrafts, which can rival in low speed operations against helicopters. It starts from an effective energy balance of helicopters during fundamental operations: takeoff, horizontal flight, hovering, and landing. The energy state of a helicopter can be written as: E = ½ mV2 + mgh + ½ I ω2 (1) where m is mass of helicopter, I is total rotor inertia, ω is rotor rotational speed. By taking the partial derivative with respect to time of equation 1, the power is expressed as dE/dt = ΔP = mV dV/dt + mg dh/dt (2) By optimizing the energy balance of the helicopter a new aircraft configuration has been obtained that allow a very high lift even at very low speed, but drastically reducing the energy consumption during horizontal flight. The total power required is obtained by rotor power and overall efficiency factor (η) and HPreq total = η HPreq rotor. By equations (1) and (2) it has been produced a preliminary optimization in different operative conditions considering a speed range from 0.5 (hovering conditions) to 50 m/s. By an accurate balance of the results, it has been identified that the most disadvantageous situation for a helicopter is forward flight. A new powered wing architecture has been specifically studied for replicating the behaviour of helicopters. Preliminary it has been defined by starting from the energy equations the main characteristics of the propelled wing. From those numerical results it has been defined a new configuration of propelled wing and the new aircraft configuration which allow adequate performance against helicopter. Those wings take a large advantage of two not common features: symmetry with respect to a vertical axis and possibility of optimizing the shape for specific missions. It has been designed and optimized in different configurations by CFD. In particular, an accurate analysis of fluiddynamic of the system allows quantifying the different effects that allows realizing an extraordinary ratio between lift and thrust producing an effective vehicle that can rival against helicopter also at very low speeds with a morphing configuration that will be presented in the final paper because of patenting reasons. Results show that the proposed innovative aircraft configuration allows hovering and very low speed flight. In particular, the conditions and the design for this kind of operation are presented even if still in initial design stage. The presented aircraft architecture can also allow inverting the direction of motion just by inverting the direction of the thrust. In this case, it will allow overcoming completely the performances of helicopters. The energetic balance of flight has been evaluated and the advantages with respect to helicopters have been finally expressed with surprising results.

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A response to industrial maturity and energetic issues: a possible solution based on constructal law

Cited by 11 publications

References 37 publications

Entrance-length dendritic plate heat exchangers

Entrance-length dendritic plate heat exchangers

Control, Propulsion and Energy Assessment of a Spherical UAS for Low Speed Operations

A New Propelled Wing Aircraft Configuration

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