Thermal Assessment for Prostheses: State-of-the-Art Review

Abbood, Sahar A.; Wu, Zan; Sundén, Bengt

doi:10.2495/cmem-v5-n1-1-12

“…The results showed that the power of the system ranges from 2.1 to 7.0 W at an air temperature of 23°C. Cooling systems for prostheses have been explored previously by Ridha and Ezzat 10 and Abbood et al 11 Cooling systems based on thermoelectric devices were used, where the required parts were cooled based on the value of the supplied electrical energy. [12][13][14][15][16] This method suffers from the problem of storing electricity in relatively heavy batteries, in addition to the low thermal performance coefficient of the system.…”

Section: Introductionmentioning

confidence: 99%

“…The results showed that the power of the system ranges from 2.1 to 7.0 W at an air temperature of 23°C. Cooling systems for prostheses have been explored previously by Ridha and Ezzat 10 and Abbood et al 11 …”

Section: Introductionmentioning

confidence: 99%

Constructal design of a PCM cylindrical heat sink with three‐branched, two‐stages dendritic tubes

Ridha,

Ezzat

2024

Heat Trans

3

0

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Amputees who use prosthetic limbs suffer from the problem of high contact temperature between the socket of the prosthetic limb and the amputated part and lack of evaporation of sweat. These conditions lead to discomfort and failure to perform functions properly. In addition, these conditions help generate ulcers and accumulate harmful bacteria in this area. This paper presents a heatsink design to extract heat from the contact area. A cylindrical heat sink is designed for phase‐changing materials with three branched tubes in two stages. The current heat sink is used to cool the contact area between the amputated part and the socket in the lower prostheses. Three distributions of pipe branches are proposed. The distribution and pipe lengths were obtained using a constructal design method. In the constructal design, the lengths of the branched tubes were the degrees of freedom, the objective function was the minimization of the inlet temperature to the heat sink, and the constraint was the volume of the cylindrical heat sink. The metabolic heat transfer during exercise was estimated and its value was used to calculate the size of the cylindrical heatsink and the selection of the phase change material by testing three of them: water, tridecane, and dodecane. It was found that water gives the highest latent heat of melting and the lowest volume in addition to its availability. On the other hand, two cooling fluids were tested: water and air. It was found that water as a cooling fluid gave the lowest flow and the largest heat capacity. Constructal theory was used to design a cylindrical heat sink using branched tubes for the coolant in two steps: the first with three branches, and the second with nine branches. The degree of freedom for constructal theory was the length of the branches through the choice of their end locations. It was found that the branches of the highest length led to a reduction in temperature from 40°C to 15.48°C compared with the single tube, which reduced the temperature to 23.87°C. All tests recorded a pressure drop within the acceptable range of 3.1–5.43 Pa for the branches examined. The research demonstrated that using constructal theory achieved the best thermal dissipation within a restricted volume.

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“…The boundary condition on u implies a tight fit of the prosthetic as no displacement occurs at the boundary. Since sockets are usually made of insulating materials [1], a Neumann boundary condition should be used. However, thermal comfort is desirable and cooling of the socket should be provided [29] in order to maintain a constant temperature, which also indicates that a Dirichlet condition can be used.…”

Section: Introductionmentioning

confidence: 99%

Uniqueness for inverse source problems of determining a space-dependent source in thermoelastic systems

Maes

¹

,

Bockstal

²

2022

Journal of Inverse and Ill-Posed Problems

0

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We study the uniqueness of some inverse source problems arising in thermoelastic models of type-III. We suppose that the source terms can be decomposed as a product of a time dependent and a space dependent function, i.e. g ⁢ ( t ) ⁢ 𝐟 ⁢ ( 𝐱 ) {g(t)\mathbf{f}(\mathbf{x})} for the load source and g ⁢ ( t ) ⁢ f ⁢ ( 𝐱 ) {g(t)f(\mathbf{x})} for the heat source. In the first inverse source problem, the source 𝐟 ⁢ ( 𝐱 ) {\mathbf{f}(\mathbf{x})} has to be determined from the final in time measurement of the displacement 𝐮 ⁢ ( 𝐱 , T ) {\mathbf{u}(\mathbf{x},T)} , or from the time-average measurement ∫ 0 T 𝐮 ⁢ ( 𝐱 , t ) ⁢ d t {\int_{0}^{T}\mathbf{u}(\mathbf{x},t)\,\mathrm{d}t} . In the second inverse source problem, the source f ⁢ ( 𝐱 ) {f(\mathbf{x})} has to be determined from the time-average measurement of the temperature ∫ 0 T θ ⁢ ( 𝐱 , t ) ⁢ d t {\int_{0}^{T}\theta(\mathbf{x},t)\,\mathrm{d}t} . We show the uniqueness of a solution to these problems under suitable assumptions on the function g ⁢ ( t ) {g(t)} . Moreover, we provide some examples showing the necessity of these assumptions. Finally, we conclude the article by studying two combined problems of determining both sources.

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