No abstract

This article presents an assessment of the external thermal load on the life support system of a solar aircraft under extreme operating conditions. The calculation was carried out for the maximum and minimum possible heat flows in the key points of the aircraft flight. In this article the conditions on the Earth’s surface and at the operating altitude of the aircraft were taken as calculated. The dependence of the quantitative changes in the heat load on the aircraft from altitude was revealed, taking into account changes of thermal properties of the environment and mechanisms of heat transfer.

Most modern aircrafts widely use air conditioning systems in order to ensure comfortable flight conditions for passengers and crew, as well as to cool the equipment of the aircraft. The aircraft in-dustry is developing every year and the requirements for such systems are growing. Preliminary calculations and analysis of such systems are of key importance in their development. Such calcula-tions will help to determine the entire further path of system development and prevent many errors. They also help to regularly improve the performance of systems, in particular, their energy charac-teristics. The main requirements for systems are reliability, energy efficiency, and weight-and-dimensional characteristicss. The paper is devoted to analysis of the efficiency of the system and its individual units. In addition, there is considered separately the influence of third-party factors on the efficiency of the system, in particular, the presence of moisture in the working air flow. This article discusses the results of thermodynamic calculation and analysis by the entropy-statistical method of the air conditioning system in various operating modes. The efficiency of the system as a whole is considered and the influence of imperfection of each of its units in particular is analyzed. The standard parameters of the operation of such systems on airplanes were taken as the initial parameters for calculating the systems. For the analysis, a system with a two-wheel turbo-cooling unit with moisture removal on the high-pressure path was selected. A schematic diagram of the system is given, formulas for calculating the minimum required work to compensate the production of entropy for the units of the system are presented. To ensure the calculations, the software complexes MathCAD, Coolprop and Matlab were used.

This article discusses a static mathematical model of the air conditioning system of a passenger aircraft with moisture control. The model was developed to calculate various operation modes of this system, for one of which the entropy-statistical analysis was performed. In the analysis, the main nodes of the circuit are considered, an assessment of their influence on the overall efficiency of the air conditioning system is carried out, as well as the advantages of the given entropy-statistical analysis method for such systems are evaluated. The mathematical model was developed in the Matlab Simulink software package.

Система кондиционирования воздуха (СКВ) авиационной техники содержит несколько воздухо-воздушных теплообменников (ВВТ). Конструктивно ВВТ обладает наибольшей металлоемкостью и высокой степени изготовления. Анализ отказов ВВТ в процессе эксплуатации позволит решить вопрос ускоренных ресурсных испытаний, что значительно снизит стоимость ВВТ. Основной целью является систематизация различных типов ВВТ по степени их тепловой эффективности, анализу отказов и определения эксплуатационного ресурса, используемых в авиационных СКВ. Проведение статистического анализа является основным способом определения показателей эксплуатационного ресурса изделия, при этом изделие должно безотказно работать довольно продолжительное время. В связи с этим оценка показателей надежности традиционными статистическими методами, требующая длительных испытаний больших объемов выборок изделий, ведет к большим временным и материальным затратам. Идеи ускоренных испытаний во многом были взяты из методов проведения усталостных испытаний материалов, в которых были сформулированы основные принципы.