A Mathematical Model of the Thermo-Anemometric Flowmeter

Optimal Design Parameters of Thermal Flowmeter for Fuel Flow Measurement

The article analyses the influence, relationship and value of the design parameters of the thermal flowmeter on its radial and axial heat fluxes in the tube. The purpose of the analyses is to check the change in the error of fuel flow measurement by the thermal flowmeter directly on the vehicle when using heating elements of different diameters. The influence of the radial heat flux of the flowmeter tube on the accuracy of fuel flow measurement is substantiated. Recommendations on the choice of design parameters of a thermal flowmeter at the stage of its design, development or use are developed under the condition of reducing the influence of the radial heat flow on the axial one, which will reduce the total error in the measurement of fuel flow rate.

Optimization of Heat Exchange Plate Geometry by Modeling Physical Processes Using CAD

This article presents the possibility of evaluating the efficiency of the heat exchange element with a special stamping plate, which is based on the results of computer simulation. The method is based on a comparative analysis of convective heat transfer models implemented in ANSYS using a k-ε turbulence model. To conduct the study, 3D models of three different types of cavity geometry formed between two heat exchange plates (flat plate, chevron plate, and plate with conical stampings) were built. Simulation was performed by finite element analysis in ANSYS for channels formed by the three types of plates, one of which is a new configuration. The results of hydrodynamic and heat exchange parameters allowed for establishing the efficiency of convective heat exchange for plates of known structures and to compare them with the proposed one. It was found that the plates with conical stamping form the smallest channels through which the fluid moves. The velocity of the coolant is uniform throughout the cross section of the channel and equal to 0.294 m/s; the value of the heat transfer coefficient is the largest of the three models and is 5339 W/(m K), while the pressure drop is 1060 Pa. Taking into account the simulation results, the best heat transfer parameters were shown by the channel formed by plates with conical stamping and the highest pressure drop. To increase the efficiency, indicated by the ratio of heat transfer coefficients to hydraulic resistance, the geometry of the plate with conical stamping was optimized. As a result of optimization, it was found that the optimal geometric parameters of the heat exchange plate with conical stamping were achieved at a 55° inclination angle and 1.5 mm height for the cone. The results of this study can be used in the design of heat exchange elements of new structures with optimal parameters for highly efficient heating of liquid coolants.

Requirements for Supporting Diagnostic Equipment of Respiration Process in Humans

There is abundant worldwide research conducted on the subject of the methods of human respiration process examination. However, many of these studies describe methods and present the results while often lacking insight into the hardware and software aspects of the devices used during the research. This paper’s goal is to present new equipment for assessing the parameters of human respiration, which can be easily adopted for daily diagnosis. This work deals with the issue of developing the correct method of obtaining measurement data. The requirements of the acquisition parameters are clearly pointed out and examples of the medical applications of the described device are shown. Statistical analysis of acquired signals proving its usability is also presented. In the examples of selected diseases of the Upper Respiratory Tract (URT), the advantages of the developed apparatus for supporting the diagnosis of URT patency have been proven.

Minimization of the Settling Time of Variable Area Flowmeters

In the article a differential equation describing transient behavior of variable area (VA) meters has been developed and validated experimentally for air as a measured fluid and for two float shapes-plumb bob and sphere. A modified version of simplex algorithm adapted for nonlinear constraint optimization problems was applied to minimize the settling time of VA meters in two cases. In the first case both the float and tube geometry were altered. In the second case only the float geometry was modified. The second case has been validated experimentally. The theory and experiment is in reasonable agreement (under 5% of full scale), which is satisfactory for the purposes of optimization of VA flowmeters dynamic performance. Analytical model of VA flowmeter has been proven to be a proper tool for optimization. Settling times obtained during the optimization process were several times shorter than these of commercially manufactured instruments. Overshoot has not exceeded the assumed value of 3%.