What are the two main techniques for thermal analysis?
What are the two main techniques for thermal analysis? Explanation: The two main thermal analysis techniques are thermogravimetric analysis known as TGA which measures the change in weight with temperature and Differential thermal analysis known as DTA which detects changes in heat content.
What are different methods of thermal analysis explain each?
Several methods are commonly used – these are distinguished from one another by the property which is measured: Dielectric thermal analysis): dielectric permittivity and loss factor. Differential thermal analysis: temperature difference versus temperature or time.
What are the main techniques for thermal analysis?
Thermal Analysis Techniques
- THERMOGRAVIMETRIC ANALYSIS (TGA)
- THERMOGRAVIMETRIC ANALYSIS WITH EVOLVED GAS ANALYSIS (TG-EGA)
- DIFFERENTIAL SCANNING CALORIMETRY (DSC)
- THERMOMECHANICAL ANALYSIS (TMA)
- DYNAMIC MECHANICAL ANALYSIS (DMA)
What are the types of thermal analysis?
The primary workhorses in the pharmaceutical sciences include, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and dynamic mechanical analysis (DMA).
What is Thermal analysis used for?
Thermal analysis is a general term defining a technique used to analyze the time and temperature at which physical changes occur when a substance is heated or cooled. Each technique is defined according to the types of physical changes being analyzed.
Why do we use thermal analysis?
Thermal analysis, as it typically records a physical property as a function of temperature and time, is an ideal method for recording the phase behaviour and stability of an API2,3. The temperature associated with the experiment can be held constant or varied in a controlled manner.
What do you mean by thermal analysis?
Definition of Thermal Analysis A group of techniques in which a property of the sample is monitored against time or temperature while the temperature of the sample, in a specified atmosphere, is programmed.
What is the thermal analysis of materials?
Thermal analysis covers a range of techniques used to determine the physical or chemical properties of a substance as it is heated, cooled or held at constant temperature.
Which analysis involves the measurement of thermal properties as a function of time?
Thermal analysis is a series of laboratory techniques that measure physical and chemical properties of materials as a function of temperature and time. Thermal analysis results provide insight into the structure and quality of both starting materials and finished products.
What are thermal events of materials?
Thermal analysis relies on material reactions to thermal energy flow in or out of solids. The thermal events examined by DTA and DSC include solid phase transformation, glass transition, crystallization and melting.
What is the factor that limits the application of this differential thermal analysis method?
Explanation: Because of the insensitivity of the DTA differential thermal analysis method, this technique has very limited applications, its main use has been in the method of cooling curves which was used to determine the phase diagram.
What is the lumped heat capacity analysis?
The lumped-heat-capacity method of analysis is used in which no temperature gradient exists. This means that the internal resistance of the body (conduction) is negligible in comparison with the external resistance (convection). i.e small h and large k. cp = specific heat of the body.
What is critical radius of insulation?
The critical radius of insulation is a counterintuitive concept within the study of heat transfer. The theory states that adding insulation to a cylindrical or spherical object will increase the rate of heat loss rather than decrease it, if the radius (thickness) of the insulation is at its “critical” value.
What is critical thickness?
The thickness upto which heat flow increases and after which heat flow decreases is termed as critical thickness. In the case of cylinders and spheres it is called critical radius. The thickness upto which heat flow increases and after which heat flow decreases is termed as critical thickness.
What are the assumptions for lumped capacity analysis?
The essence of the lumped system analysis is the assumption that the temperature of the solid is uniform within the body at all times and changes with time only, T=T(t). This assumption implies that temperature gradients within the solid are negligible.
For which material thermal conductivity is highest?
What is the criteria to apply lumped capacity model for solving heat transfer problems?
Requirements for the Model
- Thermal radiation is neglected.
- Internal thermal resistance of the solid is very low.
- Heat sources do not exist inside the solid.
- Initial temperature of the solid is uniform.
- Physical properties of the solid are constant.
- Ambient fluid temperature is constant.
What is the lumped capacitance method?
A lumped-capacitance model, also called lumped system analysis, reduces a thermal system to a number of discrete “lumps” and assumes that the temperature difference inside each lump is negligible. This approximation is useful to simplify otherwise complex differential heat equations.
Which material is suitable for lumped analysis?
Therefore, small bodies with high thermal conductiviy are good candidates for lumped system analysis, especially when they are in medium that is a poor conductor of heat (such as air or another gas) and motionless.
What is LC in heat transfer?
Lc [m] is the characteristic length of a material, h [W/(m² * K)] is the heat transfer coefficient at the material’s surface, k [W/(m * K)] is the thermal conductivity of the material. Bi is the resulting Biot number.
What is a lumped system?
A lumped system is one in which the dependent variables of interest are a function of time alone. In general, this will mean solving a set of ordinary differential equations (ODEs) A distributed system is one in which all dependent variables are functions of time and one or more spatial variables.
What is the difference between a lumped and distributed system?
The mathematical equations governing lumped elements are ordinary differential equations. In distributed elements, the physical quantities associated with the component are distributed in space. Quantities such as voltage and current are dependent on time and space in distributed elements.
What is difference between lumped and distributed parameters?
The lumped element can be represented with its parameters like resistance orinductance with its total value at a place. In these elements resistance, inductance or capacitances are distributed and cannot be separated and modelled at a single point. These are distributed throughout the circuit.
Which type of fin is more effective?
So, plate 5 will give the most effective fin type with a lower weight, surface area, size; and as a result minimum cost and maximum efficiency.
What is an ideal fin?
An ideal fin is the one whose temperature is equal to temperature of the surface. This is possible only if the thermal conductivity of fin material is infinitely high. The effectiveness of an actual fin material is always lower than an ideal fin.