An Experimental Study on External Ventilation to the Heating Performance of Household Air Source Heat Pump

The external ventilation conditions have a great influence on the heating performance of the air source heat pump (ASHP) systems. The outdoor units of residential household air source heat pumps are often installed in narrow spaces such as balconies. The ventilation conditions of the outdoor unit will influent the heating performance of the air source heat pump. It is necessary to study the effect of the outdoor unit ventilation conditions on the heating performance of residential household heat pumps. This paper experimentally studied the heating performances of an air source heat pump system with the outdoor unit mounted in a balcony in different external ventilation conditions. The results indicate that the ventilation conditions for the outdoor units have a significant effect on the heating performance of the system. When the inlet of the outdoor unit was close to the sliding door and completely blocked, the ventilation environment was the worst and the coefficient of performance (COP) was the lowest. In addition, the unfavorable ventilation environment could result in a reduction of the COP by 26.2%. When the inlet of the outdoor unit was partially blocked, the heating performance could be improved and the COP was also slightly improved. The great heating performance was obtained under the cross-ventilation condition. This paper can guide the design of the installation position of the household air source heat pump outdoor units in actual engineering.

Application of Evaporative Cooling Technology in Transformer for Mine Tunnels

The traditional dry-type mine transformer has some disadvantages, such as incomplete fire prevention, large volume, high loss and not enough environmental protection. Based on evaporative cooling technology, this paper proposes a scheme of mine transformer using fluorocarbon as coolant which can truly realize the incombustible transformer scheme and meet the strict environmental requirements. The transformer adopts three-dimensional wound core structure to reduce the loss and improve the anti-short-circuit ability. The volume of transformer is greatly reduced due to the efficient heat dissipation ability of evaporative cooling technology. The scheme of plate fin heat exchanger is more suitable for the ventilation condition of the mine. The filling technology is used to reduce the amount of expensive coolant. Through the life cycle cost analysis, evaporative cooling transformer has better economic benefits than traditional mine transformer, but also has better safety benefits. A prototype is manufactured and tested, and the results show that the prototype meets the requirements of IEC standard temperature rise limit and achieves the expected requirements.

Essential Measures for Ending COVID-19 and Other Pandemics: Congress Should Establish True Health Science

In the attached article intended for Congress and state legislatures, I prove that medicine is deeply flawed, treatment options are extremely narrow, and treatments are not unable to address multiple cause factors. Due to flaws, money influences, biases, and intention to preclude real cures, medicine is unable to use the biggest cure for COVID-19. Temperature is a factor responsible for 100 times higher incidence and death rates. Ventilation condition in existing buildings in the U.S. is the first risk factor in schools, universities, office buildings, etc. The proposed measures can completely control the pandemic, solve medical spending shortage, revive national economy, and find cures for chronic diseases.

Numerical investigation of radon dispersion and dose assessment for typical ventilation schemes with an air purifier

Radon is a radioactive pollutant that could pose hazards to the surrounding environment and people due to its radioactive decay progenies. In this study, numerical simulations of radon dispersion were conducted under natural and mechanical ventilation with an air-purifier for radon. Factors such as the air supply speed, position and air supply angles of the purifier were considered. Results showed that the increase in the air supply speed from the purifier was an effective solution to reduce indoor radon pollution. The effect was better when the purifier was in the middle of the room. The purification effect was similar when the air supply changed under natural ventilation, while purification function was more effective when the air supply angle was 60° under the mechanical ventilation condition. An effective dose estimation involving typical ventilation schemes with radon purifier was evaluated. Using this approach, the radiation effect on occupants was computed. The calculated effective dose was 0.9 mSv y−1 when the air supply speed of the purifier was 0.2 m s−1 under natural ventilation. As a result, the effective dose calculated was under the annual effective dose limit of 3–10 mSv y−1 recommended by the International Commission on Radiological Protection (ICRP) for public exposure.

The relationship between the internal condition and the ventilation environment in a modular building

This study explores the interaction between the indoor ventilation environment of a modular building and internal building elements, including relative position of modules, number and location of windows and standardized bathroom modules. The computer hydrodynamics technology was used for this research. The model was divided into three parts to simulate the ventilation environment: (i) the relative position of the module, (ii) the number and position of windows, and (iii) the position of the standardized bathroom module. The results of the simulation illustrate the need to balance the balcony space for indoor ventilation, which should be considered comprehensively during the actual design. From the perspective of the whole living unit, the ventilation condition is more advantageous when the four openings are along the external wind direction. In addition, it can improve efficiently the overall ventilation quality in the low wind speed zone by taking full advantage of the bathroom location in modular interior. In the process of a modular unit design, the relationship between standardized modules, window location, number and indoor comfort should be fully considered. With the simulation results, a relatively optimized standard of modular interior organization was established. In future, these variables can be adjusted according to actual needs.

Experimental Study on Influence of Ventilation on Trajectory Characteristics of Free Motion of Supercavitating Vehicle

In order to study the trajectory characteristics of supercavitating vehicle in free motion, a series of experiments were carried out on an unpowered vehicle under ventilation and non-ventilation conditions respectively. High-pressure gas was utilized to launch the vehicle. The flow pattern in free motion was captured by using a high-speed video camera, the variations in the motion parameters and the cavity pressure were simultaneously recorded by using the internal measuring system. The measured data under ventilation and non-ventilation conditions were analyzed in detail, giving the effect of the ventilation on the motion of the vehicle. The experimental results show that the cavitation number fluctuates around a certain value under the influence of both velocity of the vehicle and the ventilation flow rate, keeping the vehicle to stably move in the supercavitating state. Under non-ventilation condition, the vehicle moves stably at the state of supercavitating and double-cavity closed on at the cylindrical section of the vehicle. But the motion turns into instable when the cavity is closed at the shoulder of the vehicle. Therefore, to reduce the cavitation number by ventilation is beneficial to maintaining the stability of the vehicle.