Modelling of Heat Transfer Processes in Heat Exchangers for Cardiopulmonary Bypass

A model of the heat exchange process in the heat exchanger of the cardiopulmonary bypass device is proposed which allows for automation of the process of temperature regulation in the cardiopulmonary bypass with an accuracy of ±1 °C during cardiac surgery under controlled cooling and warming of the patient’s heart and brain. The purpose of this research is to create a concept and model of the temperature control circuit using the MSC Easy5 system, the creation of mathematical models of blocks of the temperature control circuit, and the description of the principle of temperature control in the cardiopulmonary bypass circuit. The model of the temperature control loop in the heat exchanger of the heart-lung machine was created using the MSC Easy5 system with a programmable microcontroller. The microcontroller implements a specialized temperature control algorithm in the C language. The model allows the creation of a full-fledged virtual prototype of a temperature control device in a heat exchanger, and helps to conduct virtual tests of the developed device at the design stage. The model identifies control system flaws and influences decisions made before producing an official prototype of the product.

The heat leakage measurement of dewars for infrared detector arrays

Consideration is given to the analysis of a number of implementation of calorimetry method of infrared detector array dewar’s heat leakage measurements. The heat leakage measurements were made both with and without nitrogen vapor heat capacity consideration. The heat exchange process between nitrogen vapor and Dewar’s well walls was analyzed. The most reliable results were achieved by means of approach with calibration.

THEORETICAL MATHEMATICAL MODELING OF HEAT EXCHANGE IN PIPES WITH TRIANGULAR AND SQUARE TURBULATORS WITH d/D=0.95÷0.90, t/D=0.25÷1.00 AND HIGH REYNOLDS NUMBERS Re=106

Mathematical modeling of heat exchange process in straight and round horizontal pipes with protrusions and d/D=0.95...0.90, t/D=0.25...1.00 of triangular and square sections with large Reynolds numbers (RE=106) are carried out on the basis of multiblock computing technologies based on solutions of factored and finite-volume algorithm of RANS equations and energy equations. It is shown that for higher square protrusions and at higher Reynolds numbers, a limited increase in NU/NUgl is accompanied by a significant increase in relative hydro resist ance in accordance with the higher Reynolds number; for triangular turbulators, this persists and even deepens.

Modelling Heat Transfer in Solar Distiller with Additional Condenser Studying

The sun is the main source of energy that reaches the surface of the earth in the form of electromagnetic radiation called solar radiation and when it reaches the outer surface of the glass hood of the solar distillation, the process of energy transferring as the heat begins. the energy transfer process between parts of solar distillates greatly controls its performance, so the greater amount of energy gained and the less energy lost, leads to higher productivity and efficiency of the solar distillery. in this paper, a mathematical model was constructed to calculate the amount of thermal energy in each part of a monoclinic solar distiller equipped with an additional capacitor during its operation. as a result of this model showed that the temperature, after a series of heat energy exchanges between the glass cover and all the internal parts of the distillate, with the absorbent part at the base of the distillate, exhibited the same behavior, which is increasing in its temperature steadily during the first hours of the day from (32.5-41.7 ) at (08:30 am) in the morning down to its top value (61.4-76.7 ) at (02:30 pm) and decline after this hour in the same bullish pattern. this is due to the greater difference between the amount of energy lost and acquired by the absorbent portion during the same daylight hours, as the amount of energy gained increases and the amount of lost energy decreases, leading to the highest energy gain and the least energy lost by the absorbent part at (02:30 pm), except the outer part of the additional condenser, which followed a similar behavior of air temperature, with its temperature gradually increasing slightly during the first hours of the day from (27 ) at (08:30 am) until it reached its peak (36.2 ) at (01:30 pm), then it decreases after this time slightly. this slight rise and slight decrease are due to the constant state of thermal balance between the two ends of the additional condenser by the heat exchange process between the outer part of the additional condenser and the cooling water.