Assessment of Thermal Performance of Semicircular Fin under Forced Air Convection: Application to Air-preheater

To meet the insatiable demand for data bandwidth in VSR (very short reach up to 300m) applications including server and routers, parallel optical interconnection offers a promising solution in terms of performance and cost effectiveness. A 12-channel pluggable paralle optical transmitter module has been developed to achieve a data rate of 2.5 Gb/s per channel. To maintain the robustness of the optical signal integrity under different environmental conditions, the thermal management is crucial. In this paper the thermal performance evaluation of the optical module was carried out through both numerical simulation and experimental verification. The optical module mainly consists of a VCSEL (vertical cavity surface emitting laser) array, a driver IC and a heat sink. Three types of heat sinks were integrated into the transmitter module separately. The thermal environments used for this evaluation include the normal and high ambient temperature, and both still-air and forced-air conditions. The ambient temperature and the wind speed were controlled by using a Wind Tunnel. The simulation was performed by using a CFD (computational fluid dynamics) program. In all the three modules, the simulation and experimental results of the junction temperature have shown good agreements. For Module 1 under the high ambient temperature, a forced-air condition was required to keep the junction temperature below 70°C. For Module 2 and Module 3, the junction temperature can be controlled below 70°C even under the high ambient temperature without using a fan.

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Shape Memory Alloy Based Rotational Actuator

Volume 4B: Dynamics, Vibration, and Control ◽

10.1115/imece2018-87646 ◽

2018 ◽

Author(s):

Nick Hofmann ◽

Michael P. Hennessey

Keyword(s):

Shape Memory ◽

Rotational Motion ◽

Thermal Analyses ◽

Peak Torque ◽

Advanced Materials ◽

Constant Torque ◽

Heating And Cooling ◽

Air Convection ◽

Technological Developments ◽

Forced Air

Due to recent technological developments in advanced materials, the integration of shape memory alloys (SMAs) into new machines and mechanisms is becoming more common and it offers tremendous potential for the future. Using currently available properties of common SMA materials, the paper’s contribution is to: Study through dynamic simulation the potential offered by SMA springs to serve as the basis for rotary actuation. In the process, the SMA displaces a rocker arm rotating about an axis to induce rotational motion of a driveshaft, in effect converting a force into rotational motion. When embedded in a cycle with heating & cooling phases and a resetting mechanism, unidirectional rotational motion can be achieved. Regarding heating and cooling cycles, forced air convection is used to reduce thermal cycle cooling and is calculated via transient thermal analyses. Using typical parameter values for the representative design considered, through forced air convection, cooling cycles are reduced from approximately 30 seconds (natural) to 5.5 seconds (forced) and as a result, a complete system cycle can occur in 10 seconds, with the applied inertial load of 2.0 kg-m2. Using MATLAB and Simulink, a nonlinear 3rd order dynamic system model was created and simulations were performed. One complicating factor concerned angular limits and the necessary thermal cycling, which was solved through appropriate sequencing and resetting of integrators for different phases. Simulation results for the design considered show that a peak torque of 1.72 N-m is possible and that relatively smooth motion and approximately constant torque output is also possible through the addition of a few more rocker arm systems, properly commutated. Lastly, the design analysis framework and results may inspire future realization of actual devices.

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