The change in total entropy implies the transfer of heat between the compound and the environment. Therefore, a magnetic material can heat or cool upon cyclically applying and removing a magnetic field, so the MCE can be used for magnetic refrigeration as an ecological alternative to gas compression - expansion refrigeration technique. Similarly, a material can change its temperature upon application of an external pressure, barocaloric effect (BCE) [2, 7]. This effect is usually investigated by two processes: the isothermal entropy change (∆S_T... ... middle of paper ... ...field and 3) both pressure and magnetic field are changed simultaneously. All these three processes were simulated increasing and decreasing temperature, showing the existence of thermal hysteresis which was ascribed to the magnetoelastic interaction.
According to Kissinger’s Equation, a plot of ln [(Tg)2/α] versus 1/Tg should be a straight line as shown in figure 4, and from its slope, the value of Eg can be calculated. And it is equal to 328.82 kJ/mol. The crystallization process can be explained by the DSC results which obtained at different heating rates. The kinetic parameters (activation energy for crystallization, Ec, and Avrami exponent, n) for the crystallization peaks determined. Kissinger method used to determine the activation energy for crystallization (Ep) considering the heating rate (α) dependence of the peak crystallization temperature (Tp) as shown in figure 5.
Differential scanning calorimeter (DSC): Abstract: The report is written to explain DSC, the thermal analysis technique. In this technique the differential analysis on the base of reference material is done at different temperature. A very close and similar technique is DTA (Differential Thermal Analysis) . In these technique the material is heated at different temperature although sometimes isothermal analysis also done for specific applications. The temperature is recorded for any heat release or absorption.
Getu, P.K. Bansal has work on Thermodynamic analysis of an R744–R717 cascade refrigeration system. In this system the design and operating parameters considered in this study include (1) condensing, sub cooling, evaporating and superheating temperatures in the ammonia (R717)high-temperature circuit, (2) temperature difference in the cascade heat exchanger, and(3) evaporating, superheating, condensing and sub cooling in the carbon dioxide (R744)low-temperature circuit. Conclusion is that an increase of superheat increased mass flow ratio but reduced COP of the system. An increase in sub cooling increased both COP and an increase in refrigerant mass flow ratios.
The different fluid pressure causes the vapor moves through the pipe and reach condenser. In condenser section, the vapor condenses and its latent heat releases and then the fluid returns from inside wick by capillary pressure to evaporator section. This study has been conducted to show the effect of using three water based nanofluids (water+ Al2O3), (carbon nanotube+water) and (water+diamond) on the heat operation of heat pipe. We also applied a new correlation for viscosity of nanofluids developed by bakhshan et al. .Finally the graphs of velocity, temperature, pressure and heat resistance of heat pipe were obtained with using the nanofluids and carbon nanotube and has been compared with conventional operation of heat pipe which uses from pure water.
What is Nusselt number? “The process of measure ratio of any heated material is called temperature measurement we can measure temperature with the help of thermocouples, Thermistors, Thermometers.” “The Nusselt number (Nu) is the ratio of convective to conductive heat transfer across (normal to) the boundary. Nusselt number is close to one. In this experiment we have to measure temperature of Nusselt number with heat transfer coefficient for flow of a horizontal cylinder here the is the diameter and length of cylinder. We have to determine heat transfer from a horizontal cylinder.
The change in enthalpy is synonymous with the change in heat. If the change in enthalpy is positive, it is an endothermic reaction. A negative answers means it is an exothermic reaction. Equation two is the equation for the enthalpy of a reaction. (Equation 2) Hrxn= Hproducts - Hreactants Calorimetry is used to measure enthalpy.
Thermal properties of the samples were carried out by Thermo gravemetric analysis (TG) and Differential thermal analysis (DTA) in air and Nitrogen atmosphere. The temperature dependence magnetization measurements were carried out using Vibrating Sample Magnetometer (VSM). To investigate the temperature dependence of magnetization, two types of magnetization measurements were carried out viz. Field cooled (FC) and Zero-field cooled (ZFC) magnetization. In ZFC measurement, the ferrite sample is cooled down to the liquid helium temperature in the absence of a field and then a moderate magnetic field is applied (500 Oe) and the temperature is gradually increased simultaneously the magnetization (M) values were recorded.
Specific Heat of Solids I. Objective The objective of the study is to explain, measure and better understand the specific heat of copper and lead using the method of mixtures. II. Theory Heat is a form of energy it is either expressed in joules, calories, or kilo-calories According to the law formulated by the French chemists Pierre Louis Dulong and Alexis Thérèse Petit, the specific heat of solids which is characterized as the amount of heat required to raise the temperature of one gram of a substance to one degree Celsius specimens are inversely proportional to their atomic weights; that is, the specific heat multiplied by the atomic weight is approximately a constant quantity for all the solid elements. (http://encarta.msn.com).
It is found that an increase in the velocity slip parameter causes decrease in the flow velocity, however an increases in the value of the thermal slip parameter causes increase in the temperature of the fluid. Ramesh et al.  studied analytically flows of Casson fluid with slip boundary conditions. Eldabe et al.  studied the problem of the boundary layer flow of MHD non-Newtonian nanofluid with heat and mass transfer through a porous medium under the effect of heat generation, radiation and chemical reaction through a porous medium.