An indirect method and procedure for determining the local heat transfer coefficient in experimental studies on the intensity of heat transfer at a gas–surface interface is described. The article provides an overview of modern approaches and technical devices for determining the heat flux or friction stresses on surfaces in the study of thermophysical processes. The proposed method uses a constant-temperature hot-wire anemometer and a sensor with a thread sensitive element fixed on the surface of a fluoroplastic substrate. A substrate with the sensor’s sensitive element was mounted flush with the wall of the investigated pipeline. This method is based on the Kutateladze–Leontiev approach (the laws of friction and heat transfer) and the hydrodynamic analogy of heat transfer (the Reynolds analogy): this is an assumption about the unity of momentum and heat transfer in a turbulent flow, which establishes a quantitative relationship between friction stresses on the heat exchange surface and heat transfer through this surface. The article presents a method for determining the speed of the developed measuring system. An example of a successful application of the proposed method in relation to the study of thermomechanical processes in the gas exchange systems of reciprocating internal combustion engines is described.

This article provides an overview of the use of supercapacitor energy storage systems in adjustable AC drives for various purposes. The structures of the power section of combined (hybrid) power supplies for vehicle electric drives (hybrid electric vehicles and public transport vehicles) and general-purpose electric drives of an industrial grade (cranes, freight, and passenger lifts) are given. This review focuses on the problems inherent in conventional solutions adopted in the implementation of the power section, as well as the effect that can be obtained when using supercapacitor energy storage systems in controlled electric drives. The topologies of reversible DC/DC converters for supercapacitor energy storage devices are considered with a comparative assessment of their advantages and disadvantages, as well as their areas of application. This paper provides an overview of the structures of automatic control systems for supercapacitor energy storage devices. The composition and principles of regulating variables, the types of regulators used, and the criteria for setting regulation systems are analysed.

In the paper, the electromagnetic compatibility of a frequency converter with a power supply is investigated. Comparison of the variants of the electric drive with conventional capacitors and supercapacitors, which are connected directly to the DC link of the frequency converter, is given. The simulation results in the MATLAB package and the experimental study of the electric drive with using the power quality analyzer are presented. The paper presents the forms of currents and voltages at the input of the frequency converter, as well as their harmonics composition. Conclusions about the influence of the supercapacitor block on the electromagnetic compatibility of electric drive to the mains are made.

The paper deals with the problem of the voltage stabilization in the DC link of a frequency converter with an PWM inverter, which is part of AC drive with a frequency method of speed control. To stabilize the voltage in the DC link, energy storage technology is used, which is implemented with using an energy storage device based on supercapacitors, which is connected to the DC link by means of bi-directional DC-DC converter. The work uses the concept of stabilizing the DC bus voltage by compensating the PWM inverter load current with the external current of the energy storage device. The energy storage device is equipped with a single-loop tracking current control system. The current control system is based on the combined control method. The aim of the work is to improve the accuracy of voltage stabilization in the DC link of frequency converter. The sensitivity of the DC link voltage to various disturbing factors is investigated. The theoretical analysis of the error coefficient of the current control system is carried out. The simulation of the electric drive is carried out without and taking into account the discreteness of the DC-DC converter. The research results can be useful in the development of supercapacitor energy storage control systems for various applications.