DOES CEMENT CURING CAUSE CONCERNING INCREASE OF THE TEMPERATURE WHEN DELIVERED IN THE HUMAN HUMERUS?

2021 ◽  
Author(s):  
MARIA LUISA RUSPI ◽  
DANIELE MARRAS ◽  
LUCA CRISTOFOLINI
Keyword(s):  
Thermal Conductivity ◽  
Maximum Temperature ◽  
Fracture Treatment ◽  
Tissue Necrosis ◽  
Fixation Failure ◽  
Maximum Temperature Difference ◽  
Factors Affecting ◽  
Human Bones ◽  
Humeral Diaphysis ◽  
Over Time

For the treatment of humeral fractures, numerous strategies exist to improve the clinical outcome of the reconstruction and to reduce the incidence of fixation failure. Injection of acrylic-based cements to reinforce the bone and/or augment the screws is one option. The heat generated during cement polymerization raises some concerns, as it could cause tissue damage. The first aim of this study was to measure the temperature over time during polymerization when acrylic cements are delivered inside the bone to treat fracture. The second aim was to assess if the ISO-5833:2002 standard can predict what happens in a real bone. Different tests were performed using two acrylic-based cements (Mendec and Cal-Cemex): (i) the ISO-5833:2002 standard (Annex C); (ii) tests on human bones (humeral diaphysis and humeral head) injected with cement to simulate fracture treatment. In the humeri, the highest temperature was measured in the diaphysis (68.6∘C for Mendec, 62.7∘C for Cal-Cemex). These values are comparable with the temperature reached in other consolidated applications (vertebroplasty). Exposure to high temperature was shorter for the diaphysis than for the head. For both cements, in both the diaphysis and the head, temperatures exceeded 48∘C for less than 10[Formula: see text]min. This is within the threshold for tissue necrosis. The ISO-5833:2002 yielded significantly different results in terms of maximum temperature (difference exceeding 15∘C) and exposure to temperature above 48∘C and 45∘C. This discrepancy is probably due to a combination of factors affecting the amount of heat produced and dissipated (e.g., amount and shape of the cement, thermal conductivity).

A Study on Storing Process of Thermoforming Using Finite Difference Method

2011 ◽  
Vol 314-316 ◽  
pp. 571-575
Author(s):  
Zhen Zhe Li ◽  
Gui Ying Shen ◽  
Xiao Qian Wang ◽  
Mei Qin Li ◽  
Yun De Shen
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Finite Difference Method ◽  
Initial Temperature ◽  
Thickness Distribution ◽  
Time Dependent ◽  
Maximum Temperature ◽  
Uniform Thickness ◽  
Maximum Temperature Difference

Obtaining a uniform thickness of the final product using thermoforming is difficult, and the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the time-dependent temperature distribution of the total sheets in the storing process was studied because the temperature after the storing process is the initial temperature of the preheating process. An analysis code for simulating the storing process was developed under the condition that the thermal conductivity caused by contact resistance between sheets was assumed as a large value. In this study, the number of sheets in the storing room was adjusted for finding out the effect of it. The analysis results show that maximum temperature difference between sheets was significantly different when adjusting the number of sheets in the storing room. The temperature distribution of the total sheets and the method for analysis in this study will be used to optimize the storing process for higher quality of final products.

scholarly journals Constructal Design of an Arrow-Shaped High Thermal Conductivity Channel in a Square Heat Generation Body

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 475 ◽  
Author(s):  
Fengyin Zhang ◽  
Huijun Feng ◽  
Lingen Chen ◽  
Jiang You ◽  
Zhihui Xie
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Heat Generation ◽  
Degrees Of Freedom ◽  
High Thermal Conductivity ◽  
Maximum Temperature ◽  
Thermal Conductivity Ratio ◽  
Maximum Temperature Difference ◽  
Conduction Model ◽  
Three Degrees Of Freedom

A heat conduction model with an arrow-shaped high thermal conductivity channel (ASHTCC) in a square heat generation body (SHGB) is established in this paper. By taking the minimum maximum temperature difference (MMTD) as the optimization goal, constructal designs of the ASHTCC are conducted based on single, two, and three degrees of freedom optimizations under the condition of fixed ASHTCC material. The outcomes illustrate that the heat conduction performance (HCP) of the SHGB is better when the structure of the ASHTCC tends to be flat. Increasing the thermal conductivity ratio and area fraction of the ASHTCC material can improve the HCP of the SHGB. In the discussed numerical examples, the MMTD obtained by three degrees of freedom optimization are reduced by 8.42% and 4.40%, respectively, compared with those obtained by single and two degrees of freedom optimizations. Therefore, three degrees of freedom optimization can further improve the HCP of the SHGB. Compared the HCPs of the SHGBs with ASHTCC and the T-shaped one, the MMTD of the former is reduced by 13.0%. Thus, the structure of the ASHTCC is proven to be superior to that of the T-shaped one. The optimization results gained in this paper have reference values for the optimal structure designs for the heat dissipations of various electronic devices.

Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics

Science ◽  
2015 ◽  
Vol 348 (6230) ◽  
pp. 109-114 ◽  
Author(s):  
Sang Il Kim ◽  
Kyu Hyoung Lee ◽  
Hyeon A Mun ◽  
Hyun Sik Kim ◽  
Sung Woo Hwang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundaries ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Maximum Temperature ◽  
Bismuth Antimony Telluride ◽  
Maximum Temperature Difference ◽  
Full Spectrum ◽  
Dislocation Arrays ◽  
Bulk Alloys

The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency of the bulk alloys, which is evaluated in terms of a dimensionless figure of merit (zT). ThezTof bulk alloys can be improved by reducing lattice thermal conductivity through grain boundary and point-defect scattering, which target low- and high-frequency phonons. Dense dislocation arrays formed at low-energy grain boundaries by liquid-phase compaction in Bi0.5Sb1.5Te3(bismuth antimony telluride) effectively scatter midfrequency phonons, leading to a substantially lower lattice thermal conductivity. Full-spectrum phonon scattering with minimal charge-carrier scattering dramatically improved thezTto 1.86 ± 0.15 at 320 kelvin (K). Further, a thermoelectric cooler confirmed the performance with a maximum temperature difference of 81 K, which is much higher than current commercial Peltier cooling devices.

COMPARISON OF HARMAN AND COOLING COUPLE METHODS FOR Z DETERMINATION

1966 ◽  
Vol 44 (5) ◽  
pp. 971-985 ◽  
Author(s):  
W. B. Muir
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Temperature Difference ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Type Apparatus

A Peltier–Seebeck or Harman type apparatus has been constructed to measure the Seebeclc coefficient, α, thermal conductivity, κ, electrical resistivity, ρ, and the figure of merit, Z, of thermoelectric materials over the range of temperature 150–300 °K while maintaining the sample in an approximately isothermal environment. Errors in the measured values of ρ, Z, α, and κ have been kept within 1, 1.5, 3, and 5% respectively. A comparison of the maximum temperature difference, ΔTmax, measured in a cooling test and the value of ΔTmax calculated from the values of α, κ, and ρ as a function of temperature measured in the Harman apparatus shows that, for five thermocouples, agreement is obtained within 1.2 °K on the average, with the greatest disparity being 2.5 °K.

Heat Recovery With Oscillating Heat Pipes

2013 ◽  
Author(s):  
Charles R. McCullough ◽  
Scott M. Thompson ◽  
Heejin Cho
Keyword(s):  
Thermal Conductivity ◽  
Temperature Difference ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pipes ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Two Phase ◽  
Maximum Temperature Difference

Waste-heat recovery applied in HVAC air systems is of interest to increase the energy efficiency of residential, commercial and industrial buildings. In this study, the feasibility of using tubular-shaped oscillating heat pipes (OHPs), which are two-phase heat transfer devices with ultra-high thermal conductivity, for heat exchange between counter-flowing air streams (i.e., outdoor and exhaust air flows) was investigated. For a prescribed volumetric flow rate of air and duct geometry, four different OHP Heat Exchangers (OHP-HEs) were sized via the ε-NTU method for the task of sub-cooling intake air 5.5 °C (10 °F). The OHP-HE tubes were assumed to have a static thermal conductivity of 50,000 W/m·K and only operate upon a minimum temperature difference in order to simulate their inherent heat transport capability and start-up behavior. Using acetone as the working fluid, it was found that for a maximum temperature difference of 7°C or more, the OHP-HE can operate and provide for an effectiveness of 0.36. Pressure drop analysis indicates the presented OHP-HE design configurations provide for a minimum of 5 kPa. The current work provides a necessary step for quantifying and designing the OHP for waste heat recovery in AC systems.

Effect of internal silver conductor on heat spreading capability of LTCC membrane

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000353-000358
Author(s):  
Claudia Reinlein ◽  
Sascha Türke ◽  
Nam Gutzeit ◽  
Jens Müller ◽  
Thomas Peschel ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Laser Power ◽  
Reference Sample ◽  
Maximum Temperature ◽  
Deformable Mirrors ◽  
Thin Membrane ◽  
High Laser ◽  
Large Heat ◽  
Heat Spreading ◽  
Over Time

LTCC membranes are used as substrates of screen printed unimorph deformable mirrors. A high piezoelectric stroke is attributed to thin substrate materials. The application of deformable mirrors with high laser loads calls for a large heat spreading capability of the deformable unimorph mirrors. A large heat spreading capability is attributed to high thermal conductivity of the materials that is not allocated by LTCC. The present paper reports on the effect of internal silver conductor (DuPont 6145) on the heat spreading capability of the LTCC membrane. Therefore, internal silver conductor is applicated into a 570 μm thin membrane on a diameter of 49.8 mm. The optical absorption of plain LTCC membranes and membranes with internal metallization is characterized by an Ulbricht sphere. Membranes with internal silver conductor and a reference sample without internal metallization (plain LTCC) are loaded with a laser beam. The absorbed laser power heats the LTCC membrane. We investigate the temperature increase upon one-Watt laser loading and prove a 37% lower setting maximum temperature (Tmax) for membranes with internal silver conductor compared to plain LTCC membranes. The characteristics of temperature over time are similar to the charging of a capacitor. The time constant for the internally metallized and plain LTCC membrane at same peak temperatures are similar. These results show the potential of internal silver conductor to increase the heat spreading capability of LTCC membranes.

scholarly journals Apparatus for routine measurements of the thermal conductivity of ice cores

1999 ◽  
Vol 29 ◽  
pp. 151-154 ◽  
Author(s):  
Crescenzo Festa ◽  
Aristide Rossi
Keyword(s):  
Thermal Conductivity ◽  
Ice Cores ◽  
Maximum Temperature ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Standard Samples ◽  
Experimental Conditions ◽  
Heating Source ◽  
Central Segment ◽  
Wire Method

AbstractAn apparatus is described for measuring the thermal conductivity of ice by the transient hot-wire method. Thermal conductivity A, is determined by tracking the thermal pulse induced in the sample by a heating source consisting of a platinum resistor. A central segment of the same platinum heating resistor acts also as a thermal sensor. A heat pulse transferred to the ice for a period of 40s gives a maximum temperature increment of about 7-14°C. In good experimental conditions, the expected reproducibility of the measurements is within ±3%. The accuracy of the method depends on whether the instrument has been calibrated by reliable standard samples, certified by absolute methods.

scholarly journals Seasonal Variations of Daytime Land Surface Temperature and Their Underlying Drivers over Wuhan, China

2021 ◽  
Vol 13 (2) ◽  
pp. 323
Author(s):  
Liang Chen ◽  
Xuelei Wang ◽  
Xiaobin Cai ◽  
Chao Yang ◽  
Xiaorong Lu
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Rapid Urbanization ◽  
The Impact ◽  
The City

Rapid urbanization greatly alters land surface vegetation cover and heat distribution, leading to the development of the urban heat island (UHI) effect and seriously affecting the healthy development of cities and the comfort of living. As an indicator of urban health and livability, monitoring the distribution of land surface temperature (LST) and discovering its main impacting factors are receiving increasing attention in the effort to develop cities more sustainably. In this study, we analyzed the spatial distribution patterns of LST of the city of Wuhan, China, from 2013 to 2019. We detected hot and cold poles in four seasons through clustering and outlier analysis (based on Anselin local Moran’s I) of LST. Furthermore, we introduced the geographical detector model to quantify the impact of six physical and socio-economic factors, including the digital elevation model (DEM), index-based built-up index (IBI), modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), population, and Gross Domestic Product (GDP) on the LST distribution of Wuhan. Finally, to identify the influence of land cover on temperature, the LST of croplands, woodlands, grasslands, and built-up areas was analyzed. The results showed that low temperatures are mainly distributed over water and woodland areas, followed by grasslands; high temperatures are mainly concentrated over built-up areas. The maximum temperature difference between land covers occurs in spring and summer, while this difference can be ignored in winter. MNDWI, IBI, and NDVI are the key driving factors of the thermal values change in Wuhan, especially of their interaction. We found that the temperature of water area and urban green space (woodlands and grasslands) tends to be 5.4 °C and 2.6 °C lower than that of built-up areas. Our research results can contribute to the urban planning and urban greening of Wuhan and promote the healthy and sustainable development of the city.

MODELING THE EFFECT OF HEAT EXCHANGE ON THE EFFICIENCY OF A THERMOELECTRIC COOLER

2020 ◽  
Vol 2 ◽  
pp. 132-135
Author(s):  
O.I. MARKOV
Keyword(s):  
Numerical Calculation ◽  
Heat Exchange ◽  
Solid State ◽  
Numerical Modelling ◽  
Temperature Difference ◽  
Maximum Temperature ◽  
Thermoelectric Cooler ◽  
Maximum Temperature Difference ◽  
Peltier Cooler ◽  
Account Heat

Numerical modelling thermal and thermoelectric processes in a branch of solid–state thermoelectric of Peltier cooler is performed, taking into account heat exchange by convection and radiation. The numerical calculation of the branch was carried out in the mode of the maximum temperature difference.

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