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This paper presents an analysis of approaches to ensuring the performance of a ramjet combustor using an unconventional method of measuring the thrust in testing an experimental model of a liquid-fuel combustor under flight conditions simulated by a fired heater. The thrust and drag of the combustor model were measured in firing tests with an attached air duct using a thrust meter. Thrust is a parameter that characterizes the energy potential of any engine. The conventional method of determining the thrust and economic characteristics of a heat engine involves lengthy multi-parameter studies and calculations of the operation performance. The new method allows one to detect the effect of any parameter or element of the structure on the physical process in a combustor in units of the developed thrust and evaluate the change in any parameter by the thrust level directly in firing tests. The proposed thrust measurement system makes it possible to refine the strategy of implementing the combustor operation at an early stage of testing, thus reducing the amount of intermediate calculations and saving a huge amount of time and money. This, combined with static pressure measurements along the combustor length, allows a guaranteed prediction of the direction of search for improving the operation performance. Ways are shown to improve the ramjet combustor performance using a thrust meter to evaluate the overall engine performance under conditions of limited technical and methodical possibilities in firing tests. [ABSTRACT FROM AUTHOR]

The smoke layer height in the ship engine room under forced ventilation has been experimental and theoretical investigated in this work. A series of test were carried out in a scaled engine cabin experimental platform to obtain the influence of air supply volume and air inlet height on the burning parameters, including the mass loss rate, smoke temperature, etc. The research results show that under the experimental conditions, the fire source mass loss rate increases exponentially, and smoke layer height also increases gradually with the increase in the air supply volume. The empirical formula of smoke layer height under different air supply conditions was given. Then, a prediction model of smoke layer height under different forced ventilation conditions was constructed through theoretical analysis based on conservation equations. Within the range of experimental air volume and air inlet height, the relative error between theoretical prediction results and experimental results was less than 11%, which could effectively predict the smoke layer height in the ship cabin fire. [ABSTRACT FROM AUTHOR]

Modeling of the aerodynamic processes involved in the ventilation of a large production enclosure containing electrical equipment requiring special conditions for air humidity and temperature was performed. A physical-mathematical model of the aerodynamics of ventilation of a production enclosure is presented, taking into account heat exchange with air and the surface of the equipment present in a building and mass exchange with the ambient environment by air filtration through the structural elements. The computational results for non-stationary displacement of air with high humidity from the building by means of ventilation with dried air are presented. The characteristic time of purification of air from excess moisture with air supplied to various parts of a building was determined. [ABSTRACT FROM AUTHOR]

An experiment has been carried out for examining the performance of an air conditioning unit under constant outdoor wet-bulb temperature and varied dry-bulb temperature. During the experiment, the wet-bulb temperature of the compartment for outdoor unit was maintained at 22 °C and the dry-bulb temperature was varied from 24°C to 36°C. The increase of outdoor air temperature results in the increase of supply air temperature, discharge temperature, suction temperature, and liquid line temperature. These cause the degradation of the air conditioner performance. An increase of power consumption by 1.4% and decrease of cooling capacity by 0.8% were observed for each 1°C increase of outdoor air temperature. As a result, the energy efficiency ratio drops by 2% for each 1°C increase of outdoor air temperature. [ABSTRACT FROM AUTHOR]

Background: Airline crew members report adverse health effects during and after inhalation exposure to engine oil fumes sourced to the air supply system onboard commercial and military aircraft. Most investigations into the causal factors of their reported symptoms focus on specific chemical contaminants in the fumes. The adverse health effects reported in aircrew exposed to the aircraft air supply, bled unfiltered off the engine or Auxiliary Power Unit (APU) may be related to particulate exposures, which are widely known to effect health. While oil contaminates the aircraft air supply, some suggest that this will only occur when there is a bearing seal failure, others document that there is low level oil contamination of the air supply during normal engine operation. This brief pilot study explores whether particulate exposure may be associated with the normal engine/APU and air supply operation and to therefore increase the understanding that UFP exposures may have on crew and passengers.Methods: An ultrafine particle counter was utilised by an experienced airline captain in the passenger cabin of four short-haul commercial passenger aircraft. All flights were under 90 min on aircraft from two different carriers ranging from 7 months to 14 years old.Results: UFP concentrations showed maximum concentrations ranging from 31,300 to 97,800 particles/cm3 when APU was selected on as a source of air on the ground and with engine bleed air and the air conditioning packs selected on during the climb. In 2 of the 4 flights the peaks were associated with an engine oil smell. Increases in UFP particle concentrations occurred with changes in engine/APU power and air supply configuration changes.Conclusions: This study identified increases in UFP concentrations associated with engine and APU power changes and changes in air supply configuration. These results correlated with times when engine and APU oil seals are known to be less effective, enabling oil leakage to occur. The concentrations reached in the passenger cabins exceeded those taken in other ground-based environments. UFP exposures in aircraft cabins during normal flight indicates there will be health consequences for long serving aircrew and some passengers. [ABSTRACT FROM AUTHOR]

• The system is applied to buildings with high moisture load. • Two-stage air dehumidification is adopted to distribute moisture load. • Seven operating modes are designed to match various environmental conditions. • Energy efficiency increases 3.19%-10.57% by regenerated air heating. • The better system performance could be obtained at low ambient air enthalpy. With the higher demand for indoor thermal comfort and the accurate control of air temperature and humidity, energy consumption in air conditioning systems is increasing over these years, especially for buildings with high moisture load such as natatoriums. However, freezing dehumidification is still widely adopted in eliminating moisture load, which requires lower evaporating temperature and causes excessive energy consumption. To improve energy utilization and efficiency, a heat pump-driven liquid desiccant dehumidification system is proposed in this research, the surface condenser and liquid desiccant dehumidifier are adopted to realize two-stage air dehumidification. In the summer condition, the solution in regenerator is heated by the condenser of heat pump and the residual heat is to heat the regenerated air, and the cooling capacity of heat pump is applied to the surface condenser and terminal heat exchanger, simultaneously the solution in dehumidifier is cooled by cooling tower. Under the meteorological conditions in Nanjing, the coefficient of performance could reach 6.148 in this proposed system, and compared to conventional air source heat pump dehumidification air conditioning system, the rising ratio of energy efficiency is between 11.4% and 80.7%. Eight cities in China are selected to analyze the energy-saving effects, and energy consumption could be reduced by 31.9%-63.2%, the result demonstrates the superior energy-saving potential and application prospect of the heat pump-driven liquid desiccant dehumidification system. [ABSTRACT FROM AUTHOR]

The Dynamic Pressure Regain Method, a new design method for uniform air supply, was proposed in this paper, based on the principle of total pressure balance. It can achieve uniform air supply by keeping equal dynamic pressure in adjacent sections of the main duct that opens up a new field for the design of uniform air supply duct system. Research was carried out through numerical simulation and full-scale experiment. First, the design steps of this method were proposed according to the flow characteristics in the duct. Then the recommended range of air velocity ratio was determined by numerical simulation calculation, and the resistance calculation formulas of the duct under this method were fitted. Finally, the full-scale experiment was carried out for the working conditions of inlet air velocity of 4 m/s and 5 m/s to verify the results of numerical simulation, including the total pressure balance, the uniformity of air supply system, the resistance calculation formulas of duct and the verticality of outlet airflow. The results showed that with a constant air velocity of the main duct sections, the variation of the total pressure loss was within 5 %, thus satisfying the total pressure balance; With a 0.6–1.0 air velocity ratio of the branch to main duct, the air volume imbalance rate of the branch duct was lower than 10 %; The error of local resistance calculation formulas of the duct system was no more than 3 %. The airflow deflection angle travelling out along the branch duct walls was within 20°. This complete design method of uniform air supply satisfies the total pressure balance and features simplicity, which decreases the air volume imbalance rate by 84 % compared with the static pressure regain method. Besides, when the size of the inlet duct remains constant, that of the design model will not change with the inlet air velocity. In addition, this study proposed the resistance calculation formulas that conform to the characteristics of its design model. [ABSTRACT FROM AUTHOR]

Studies on the thermal environment of the electronic radar shelter have been mainly focused on the simulation of the unmanned thermal environment, and there have been few studies on experiments in the thermal environment. Additionally, a comparative study of the experimental results from manned and unmanned shelters has been missing. In this paper, we experimented in thermal environments of manned/unmanned shelter under different air supply conditions. The experiment was divided into cooled, ventilated, and heated trials analyzing three aspects: (1) The average temperature distributions of walls, air inlet points, air outlet points, and surfaces were measured over time under different conditions in an unmanned shelter. The temperature distribution curve was fitted into the function. (2) Based on different working conditions, the temperature distribution experiments were carried out in three different areas for subjects wearing short or long clothing respectively. (3) The wind speed was measured at each measuring point in the air supply pipeline under different working conditions. The wind speed distribution was detected on the setting surfaces. The experimental results show that: (1) The air does not gradually tend to steady state with the time, and under different conditions, the air temperature obviously differs. (2) The clothing selection, air supply conditions, and locations of measuring points have significant influences on human body temperature distribution and left–right difference. (3) The mixing of the thermal plume caused by the vertical temperature difference of the human body and the jet generated by the mechanical air supply will reduce the wind speed of the airflow in the cabin, the adsorption of the jet to the bulkhead, and the stability of the airflow. The experimental data can provide the initial and boundary conditions for the simulation of the shelter. The results can provide a reference for the study of fluid control methods, the setting of thermal boundary conditions, and the simulation of the influence of thermal plumes on the airflow distribution. The experimental study in this paper has filled in the blanks regarding experimental study in electronic radar shelters. It has important research value and practical significance. [ABSTRACT FROM AUTHOR]