The operating principle of the electronic expansion valve is based on an electromagnetic or stepper motor drive. The controller receives signals from temperature and pressure sensors, and after calculation, outputs a pulse width modulation (PWM) signal to the stepper motor or electromagnetic coil, which drives the valve needle up and down, thus changing the size of the valve opening, and realizing the precise control of the amount of refrigerant entering the evaporator.

Guests from outside the university mainly included: Prof. Fan Xin, Secretary of the Party Committee of New Ziguang Group, Mr. Zhang Jie, President of China Association of Survey and Design, Chief Engineer of Beijing Architectural Design and Research Institute, and Prof. Zhu Yingxin, Chairman of the Teaching Guidance Sub-committee of the Higher Education Schools Specialized in Building Environment and Energy Application Engineering (hereinafter referred to as the “China Association of Survey and Design, Building Environment and Energy Application Sub-committee”).

When he first began to study evaporative cooling technology, Gu Guobiao was only 22 years old and had just joined the recently established Institute of Electrical Engineering. “Not to do with foreign duplication of things, to do one or two things beyond the foreign.” This idea, once regarded as “ridiculous”, became the lifelong belief of him and his team. For decades, they have been thinking about how to apply evaporative cooling technology to a broader field, not only to meet the country's major needs, but also to play a role in the main battlefield of the national economy.

More than seven hundred representatives from Shenzhen Development and Reform Commission, Shenzhen Housing and Construction Bureau, Shenzhen Construction and Public Works Department, Shenzhen Futian District, Nanshan District, Guangming District, Longgang District, Longhua District, Shenzhen-Shantou Cooperation District Construction and Public Works Department, Shenzhen Survey and Design Industry Association, 389 member design units, chief engineers, deputy chief engineers, engineers, construction and maintenance of high efficiency air-conditioning systems for district cooling, equipment and material manufacturers, research and development units attended the meeting. More than seven hundred representatives attended the meeting.

HVAC engineering equipment installation is an important process in construction engineering related to the use of functionality, in the air conditioning and ventilation project, due to the air duct production and installation quality problems caused by insufficient air supply, air leakage over the specification requirements, resulting in waste of energy, lack of heat and air conditioning and ventilation project operation is unstable and other phenomena, which affect the normal operation of the air conditioning.This paper focuses on the production, installation and quality control of HVAC engineering ducts are analyzed and discussed, aiming to improve the quality of HVAC installation.

The Beijing Residential Heating Contract (Area-based Billing Version) specifies that during the heating period, under normal weather conditions, Party B shall ensure that the temperature in Party A's bedroom and living room is not lower than 18℃ in residences that meet the requirements of the current National Residential Design Code or residences that have undergone modifications to the building envelope or the heat supply system;