Thermal Evaluation Method Research Articles

A reduced-scale experimental method for the thermal evaluation of building envelopes outfitted with phase change materials

A reduced-scale experimental method is originally proposed for the thermal assessment of building envelopes containing phase change materials (PCMs), including PCM-filled components, walls, panels, and roofs. The method includes a combination of advantages such as a hand-built test rig, freely set and precisely controlled boundary conditions, broad component adaptations, high efficiency, data reproducibility, and low manufacturing cost. A dynamic simulator is developed for method description and application. The results show that thermal insulation material (TIM) considerably increases the value of wall decrement factor (DF) index, but has little effect on time lag (TL) value, while PCM significantly increases both indexes. In addition, PCM used as a single layer is found to be significantly better than the case of multiple PCM-filled cavities in concrete masonry units (CMU) blocks. The thermal performance is improved when the temperature at the PCM location is close to its phase change temperature. • A new method for thermal evaluation of PCM-outfitted building envelopes is presented. • The approach is applicable to insulation and PCM-outfitted walls, panels, and roofs. • The method includes the combination of multiple advantages compared to existing ones. • A dynamic wall simulator was established for method description and application. • Typical measurements using this method together with analysis were conducted.

Method for thermal evaluation of automotive gearbox packages taking into account load point-dependent oil distribution

The spread of all-electric drives is steadily increasing in all sectors of road transport. Due to the constantly increasing demands on efficiency and performance by legislation and customers, it is necessary to continuously push the system limits of the powertrains. This paper presents an approach that performs an initial thermal system analysis based on a first gearbox configuration and efficiency calculation. Here, the componentwise loss calculation is used to identify thermal hotspots within the gearbox stage. The basis of this analysis is the thermal network method. For the approach, the gearbox elements gear, bearing, shaft, seal and housing are broken down into standard thermal elements to be created automatically for any subsequent gearbox configuration. The linking of these elements to each other is also standardised and automated comparably. An extensive simulation study is carried out using the smoothed particle hydrodynamics method to consider the load point-dependent oil distribution, which enables an initial estimate of the oil distribution. The thermal network filled in this way is then solved on a time-step basis, allowing dynamic load cases to be considered. The quality of the method is validated within the paper using the VW ID 3 gearbox as an example. Due to the use of a series gearbox, the validation was carried out on the basis of the accessible housing temperatures. These already show good convergence of the method compared to other existing approaches, which reinforces the necessity of conducting further experimental studies.

PMV as a thermal evaluation method for air-conditioned spaces in hot climates: a systematic review

The homogeneity of the subjects that were studied to produce the PMV model developed by Fanger and the evolution of the physical environment have an impact on the usability of the model. Many studies show that the PMV model does not represent the real thermal sensations of the occupants of the analyzed building. The purpose of this review is to identify and group the studies that show some discrepancy between the PMV and the opinions of the subjects concerning modern climatized field environments in hot climates around the world. The PRISMA statement was used to recover and analyze the articles, and 23 studies were selected for this review. The majority of the articles indicated that the PMV model is not suited to evaluate this kind of environment.

Apparatus and method for thermal evaluation of any thin material

This chapter describes the process of atomization and the means by which it is brought about. In spray combustion, it is necessary to atomize and distribute the liquid fuel in a controlled manner within the combustion chamber. The performance of the combustion unit is critically dependent upon the drop size produced by the atomizer and the manner in which the combustion air mixes with the droplets. Atomizers produce a fine spray of liquid by injecting a narrow diameter jet or by increasing the surface area of a sheet of the liquid until it becomes unstable and breaks down. The exact mechanism is dependent upon the particular form of atomizer being considered and the nature of the liquid being atomized, however, the basic mechanism always involves the formation of unstable columns (or threads) of liquid which break down into rows of droplets. The process of atomization can be accomplished in a number of ways in practice which are usually grouped according to the source of energy used. These are (a) by forcing the liquid at high pressure through an orifice as in pressure jet atomizers, (b) by passing a stream of gas at high velocity over the liquid surface so that waves are generated which become extended into thin films as in the twin-fluid atomizer, (c) by impinging one liquid jet upon another liquid jet, (d) by the use of centrifugal forces as in the rotating cup atomizer, and (e) by the use of ultrasonic waves, which are propagated through the liquid. Some devices may use a combination of the techniques and these are termed as hybrid atomizers.

Thermal evaluation of food processes: The role of a reference temperature

Thermal evaluation methods for food processes are derived from either the Arrhenius or the Bigelow models, among them the thermal death time method (TDTM) with z = 10°C and the equivalent point method (EPM) are of particular interest. Incorporation of a reference temperature ( T Ref) into these two methods is examined for both low- and high-temperature thermal processing. Four examples are presented, covering batch and continuous operations. For T Ref = 121·11°C, the TDTM for a typical canning operation yields a processing time 7% larger than that of the EPM; by contrast, applying the TDTM to continuous processes may result in large underestimations of the processing time, i.e. between 30 to 40% lower than those of the EPM. To avoid such underestimations, a new T Ref = 145·0°C is proposed, which is obtained by setting the first derivative of the Arrhenius equation equal to l z . In this way, the design of thermal processes can be achieved with only small overestimations or negligible underestimations. In addition, the EPM makes it possible to evaluate easily F and G values for the Bigelow and Arrhenius models, respectively.

Equivalent-point method for thermal evaluation of continuous-flow systems

Etablissement d'une methode graphique d'optimisation des traitements thermiques en continu des produits liquides

System Design and Calibration of a Continuous Flow Apparatus for Kinetic Studies

ABSTRACTA heat exchange apparatus is described to determine reaction kinetics of fluid food constituents during continuous flow. During operation fluids are exposed to well defined thermal treatments. The thermal evaluation method associated with the apparatus allows a variety of effects to be examined rapidly (i.e. pH, supporting media, level of concentration, temperature range etc.). In addition, kinetic data generation at processing conditions simulating actual conditions (velocities, Reynolds numbers, Nusselt numbers, shear stress at the wall, etc.) is possible. Description of the design and calibration procedure is given. Design flexibility allows for constituent examination at any time‐temperature range useful to the food processor.

Short-Time Thermal Life Evaluation of the Rotating Machinery Insulation Systems by the EGA-GC Method

Motorette test based on IEEE Std. 275 have been usually adopted as a thermal evaluation method for rotating machinery insulation. There are some problems in performing thest tests. The tests required a considerably time. And, as the tests predict the life at an operational temperature by an extraporation method based on the data at higher temperatures, there is a possibility of missing a change in the temperature dependence of the thermal degradation mechanism. Therefore, the thermal life evaluation method by an EGA-GC (Evolved Gas Analysis-Gas Chromatograph) was examined in comparison with the motorette test method.