DETERMINATION OF THE AVERAGE WALL TEMPERATURE OF THE PLATE IN A RECUPERATIVE HEAT EXCHANGER WITH A CORRUGATED MESH INSERT

This article discusses the issue of determining the value the average wall temperature of the plate of a recuperative heat exchanger type “air-to-air” with a corrugated mesh insert based on the results processing the data of a physical experiment to determine the thermohydraulic characteristics such heat exchange surfaces. It has been established that the temperature fi eld of heat exchange surfaces of this type is nonuniform, depends on the conditions of heat exchange and hydraulic regimes of air fl ow. Therefore, the adoption of the arithmetic means value of the measured surface temperatures as the calculated average temperature of the heat exchanger wall entails signifi cant errors in the subsequent processing of experimental data and fi nal the values of the heat transfer coeffi cients, the values the Nusselt criterion and the criterion equations of heat transfer. It is proposed to determine the average value the wall temperature of the heat exchanger based on the results of measurements the wall’s temperatures, the estimate of the coordinates the center of distribution the results of measurements the wall temperatures, the equations of heat balance and heat transfer.

Experimental studies of new design solutions for the fencing of refrigerated car and container bodies

Objective: To choose materials and technical solutions for thermal insulation in the structure of the fencing of refrigerated car and container bodies. Methods: Experimental studies of the thermal properties of the selected materials were carried out on a physical model using climatic and test chambers, analytical calculations using thermal conductivity equation. Results: The thermal properties of the thermal fencing structures of the body of refrigerated cars and containers were determined. Practical importance: New materials reduce the heat transfer coeffi cient of the fence, which will reduce fuel consumption and increase the safety of perishable goods, reduce weight and increase the volume of the body

Automated analysis technology for the transport superstructure heat transfer coeffi cient using a remote server

The main parameter determined in heat engineering tests of heat insulated cars superstructures or the locomotive operator’s cabs is the heat transfer coeffi cient К. The study introduces automated analysis technology for the heat transfer coeffi cient К of enclosure structures of the heat insulated transport means using a remote server. The underlying method provides coeffi cient K of the heat insulated transport means without additional work and time loss for complicated calculations. Personnel of test laboratories involved in heat engineering tests of vehicles possess tools for remotely calculating К, from any point in the world with internet access. To obtain К three controlled parameters measured during the heat engineering tests for 5.5 h including: the difference of the inside and outside temperature of the test object superstructure, total power of the electric heaters and geometric area of the heat transfer surface are sent to the server, after which the user promptly receives the calculated К. The economic effect of introducing the proposed technology for vehicle manufacture is the absence of required tests conducted at the test center; for an operating company — a signifi cant reduction of the idle time of the vehicle at the test center directly affects the loss of profi t. The proposed technology expands the area of operation of the test centers, while calculated К values are offi cially input into the data sheet of the vehicle.

STUDY OF HEAT TRANSFER OF A HEATER FOR VARIOUS INSTALLATION METHODS

Analysis of numerically simulated convective heat transfer for a variety of heater installations is presented. A critical review of the existing method of energy effi ciency assessment, which is based on empirical coeffi cients, is given. Numerically verifi ed nondimensional heat transfer coeffi cients for eight installations of the heater are presented. The results were validated with the adopted experimental data. Sensitivity analysis of heat transfer intensity towards heat carrier temperature for a variety of heater installations is presented.

DESIGN AND STUDY OF EXCHANGERS WITH PRESSURE GRADIENT HEAT INTENSIFIERS

This paper is presented the numerical study of local heat transfer in the turbulent boundary layer with longitudinal pressure gradient. The study is based to free software with open source code (Salome and Code_Saturne) has been based by RANS approach and empirical models of turbulence. Validation of mathematical models and software is based by collation numerical results with the results of experimental study of fl ow characteristics in a turbulent boundary layer of longitudinal pressure gradient and high turbulence intensity (Epik E. Ya., NASc of Ukraine). The validation had a high qualitative coincidence of the fl ow characteristics determined as a result of the simulation with experimental data. We designed two constructive schemes of heat exchangers for air. This study presents a calculation plan for these heat exchangers. Results of the study are showed that the use of gradient heat exchange intensifi ers leads to an increase in the heat transfer coeffi cient from air to 17 %.