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The purpose of this paper is to develop a numerical model to simulate the flow field as well as the conjugate heat transfer during unsteady cooling of a flat plate with a single submerged water jet. At wall temperatures above the liquid boiling point, the vapor formation process and the interaction of the vapor phase with the developing jet-flow field are included.

The time-dependent flow and temperature distribution during all occurring boiling phases as well as the local and temporal distribution of the heat transfer coefficient on a flat plate can be simulated.

The influence of the liquid jet flow rate (10,800=Re_d=32,400) and the nozzle distance to the plate (4=H/d=20) on the transient cooling process are analyzed. This includes the time-dependant positions of the transition regions between the boiling phases on the plate as well as the temperatures at these transition regions. Additionally, the local heat transfer rates are a direct result of the unsteady cooling simulation.

A single model approach is developed and utilized to simulate the unsteady cooling process of a flat plate with an impinging water jet including all occurring boiling phases.

By modeling and analyzing the two-phase mechanical seal of the fan-shaped groove end face, which is prone to phase change, an effective method to study the flow field of the mechanical seal when both cavitation and boiling exist simultaneously is found.

Based on the finite volume method, a fluid model was developed to investigate a two-phase mechanical seal. The validity of the proposed model was verified by comparing with some classical models.

By modeling and analyzing the two-phase mechanical seal of the fan-shaped groove end face, which is prone to phase change, the analysis of the gap flow field of the mechanical seal was realized when cavitation and boiling existed simultaneously.

Based on the model proposed for different conditions, the pressure and phase states in the shallow groove sealing gap were compared. The phase change rate between the mechanical seal faces was also investigated.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0537/

The purpose of this paper is to focus on the application of the Trefftz method to the calculation of the two-dimensional (2D) temperature field in the boiling refrigerant flow through an asymmetrically heated vertical minichannel with a rectangular cross-section. The considerations were limited to determining the temperature of the continuous phase – liquid for bubbly and bubbly-slug flow. The numerical solution found with the Trefftz methods was compared with the simplified solution. For nucleate boiling, heat transfer coefficient at the heating foil – liquid contact was determined.

The Trefftz method was used to determine 2D temperature distributions for the glass pane, the heating foil and the boiling liquid. The temperature fields were approximated by the sum of the particular solution and the linear combination of suitable Trefftz functions. Coefficients of linear combination were computed using experimental data, including heating foil temperature measurements obtained with the liquid-crystal method and experimentally determined void fraction. The computations were based on the Trefftz method supplemented with the adjustment calculus.

The way of solving direct and inverse problems of heat conduction in solid bodies (isolating glass, heating foil) and in liquids (boiling refrigerant flowing through the minichannel) was presented. For the first time, both 2D temperature fields for the heating foil and the boiling liquid were calculated while simultaneously using the Trefftz method. The known temperature values of the foil and liquid allowed the calculation of the heat transfer coefficient and the heat flux at the heating foil-liquid contact. Adjustment calculus implemented into the Trefftz method was used to smooth the measurement data and to reduce their errors.

The approach proposed in the paper can be applied to determining 2D temperature field, heat flux and heat transfer coefficient in direct and inverse problems concerning two-phase flowing miniature compact heat exchangers.

The paper presents a novel implementation of the Trefftz method to simultaneous solving an inverse problem in the heating foil and the contacting flowing liquid.

The purpose of this paper is to investigate measurement and regulation of saturated vapour height level in vapour phase soldering (VPS) chamber based on parallel plate capacitor and retaining a stable saturated vapour level above the boiling fluid, regardless of the quantity and size of assembled components.

Development and realisation of capacitance sensor that sensitively senses the maximum height level of saturated vapour above the boiling fluid in the VPS chamber was achieved. Methodology of measurement is based on capacitor change from single air to a parallel plate, filled with two dielectric environments in a stacked configuration: condensed fluid and vapour (air).

An easy air plate capacitor immersed in the saturated vapour above the boiling fluid can serve as a parallel plate capacitor owing to the conversion of the air to the parallel plate capacitor. A thin film of fluid between the two capacitor plates corresponds to the height of the saturated vapour, which changes the capacity of the parallel plate capacitor.

Introducing the capacitive sensor directly into the VPS work space allows to achieve a constant height level of saturated vapour. Based on the capacity change, it is possible to control the heating power. There is a lack of information regarding measurement of stable height of vapour in the industry, and the present article shows how to easily improve the way to regulate the bandwidth of saturated vapour in the VPS process.

Cassava production surged noticeably in Southeastern Africa beginning in the 1990s. The purpose of this paper is to examine the commercial responses and food security consequences of cassava production growth in the region.

The paper incorporates a mix of quantitative analysis, based primarily on original analysis of national farm household survey data, together with key informant interviews with value chain participants in the three neighboring countries of Malawi, Mozambique and Zambia.

In the cassava production zones, cassava's high productivity translates into per kilogram carbohydrate costs 60 per cent to 70 per cent of the cost of cereals such as maize and wheat, thereby opening up a range of profitable opportunities for commercialization of cassava‐based foods, feeds and industrial products. Despite this potential, cassava commercialization in Southeastern Africa remains in its formative stages, with only 10 per cent to 30 per cent of production currently marketed. Unlike West Africa, where cassava commercialization has centered on marketing prepared cassava‐based convenience foods, the emerging cassava markets in Southeastern Africa have centered on fresh cassava, low value‐added cassava flour, and experiments in industrial processing of cassava‐based starches, biofuels and feeds. Strategic investment in a set of key public goods (breeding, training in food sciences and food safety, and research on in‐ground cassava storage) can help to shape this transition in ways that benefit both commercial interests and the food security of vulnerable households.

The paper compares cassava commercialization across differing agro‐climatic zones, policy environments and food staple zones.

In a fuel tank, an upstanding tubular guide member extending through said tank but not communicating therewith, a movable member slidable longitudinally within said guide member, a normally inoperative pawl and ratchet device associated with said slidable member, and said guide member, magnetic flotation means outside of and guided vertically by said guide member adapted to move said pawl and ratchet device into positive relative operative engagement when the pawl piece comes within the influence of the field of said magnetic means and thereby limit the upward range of movement of said slidable member and means for indicating the movement of said movable member.

A numerical study has been made to investigate the effect of internal heating and precursory cooling during quenching of an infinite tube. The finite difference solution gives the quench front temperature as a function of various model parameters such as Peclet number, Biot number and dimensionless heat flux. The parametric dependence of the rewetting rate is obtained by the condition that the surface can only be wetted when its temperature is below the quench front temperature. Also, the critical heat flux is obtained by setting Peclet number equal to zero, which gives the minimum heat flux required to prevent the hot surface being rewetted. The numerical model is validated by comparing the results with known closed form solutions.

With the increased use of surface‐mounted devices, both the component density and the board complexity are greatly increased on many circuit pack assemblies. Good solderability for the components as well as for the printed circuit boards has become one of the most important elements in achieving the ultra‐high efficiency and quality required of an assembly soldering process in today's competitive environment. Solderability evaluation generally uses the ‘dip and look’ method that relies entirely on the individual inspectors' often inconsistent interpretations resulting from the examination of the specimen dip‐tested in a molten solder bath. This method is subjective, so the results can vary from person to person and from day to day. In addition, the sensitivity of such a method is inadequate in discerning the differences in solder wetting characteristics of very small device leads and terminations. Consequently, components with marginal or even bad solderability may pass through inspection and move onto the production line to cause many easily avoidable defects and their subsequent repairs. A sensitive and quantitative wetting balance method has been studied with the purpose of developing a better alternative to the ‘dip and look’ procedure. Special sample holders and test conditions have been developed for testing various types of components and printed circuit board coupons. Examples of solderability testings are provided to illustrate the capability of the instrument when proper testing procedures are followed. More effort is under way to simplify the test procedure, and to establish a practical solderability test standard for the wetting balance method.

Specialised surface coatings can reduce maintenance costs Controlled research and development techniques, when employed effectively, have brought several UK paint manufacturers in line with American competition for petro‐chemical plant protective coatings.

The purpose of this paper is to present a novel approach on the process zone characterization for direct feedback regarding the state of vapour, in order to assure a better monitoring, control and understanding of the process.

Different pressure sensors were applied in an experimental vapour phase soldering (VPS) station, where the hardware setup was dedicated to the current experiments. Static and dynamic pressure values were analyzed and correlated with additional thermal measurements.

The results reveal the dynamics of the vapour blanket generation. The correlated measurements show different stages of the process initialization, highlighting better accuracy than sole temperature measurements of saturated vapour identification. It is possible to trace the height of the available saturated vapour blanket with static pressure measurements.

The VPS process may benefit from the more precise saturation detection, giving better control on the heat transfer, enabling more efficient production with the reduction of idle time, and resulting in better soldering quality.

Reducing the idle time of the VPS stations may result in better efficiency and smaller power consumption, reducing the environmental impact of the method.

The presented methods provide a completely novel approach from the aspect of process zone state variables and parameters characterization, focusing on pressure measurements.