针对地铁车站侧向机械排烟系统中的烟气吸穿现象,本文在排烟口下沿加装排烟挡板以提高机械排烟效率.应用火灾模拟软件FDS数值模拟计算站台内烟气温度分布,排烟口的流场分布,压力损失增加量和排烟口CO体积浓度等,分析了排烟挡板的宽度和设置方式对机械排烟中烟气层吸穿的影响.研究表明,排烟挡板的设置有利于避免烟气吸穿现象的发生,改善机械排烟效果.排烟挡板宽度为0.6 m,角度为30° 时机械排烟效果最好.
Thermal comfort has become an important index to evaluate car performance. Accurate prediction of passenger thermal sensation is the key to evaluate thermal comfort of car. In this paper, the steady-state thermal environment of the car in summer was tested and the environment parameters of driver were measured. The Predicted Mean Vote（PMV） was calculated to predicted the whole thermal sensation of the driver. The sensitivity of parameters which influence PMV was analyzed quantitatively by Python. Finally, the PMV was corrected by thermal adaptability theory and compared with subjective thermal sensation vote. The results show that clothing insulation and activity level can significantly affect PMV, which need to be accurately measured in the test. The sensitivity of environmental parameters to PMV from high to low is air temperature, mean radiation temperature, air velocity and relative humidity,which provides a reference for the prediction of the driver’s thermal sensation. The PMV, which was corrected by expectaion fator, can predict the whole thermal sensation accurately.
In order to study the effect of heat pipe cooling turbine blades, a transient dynamic mesh model was used to simulate the rotation process of a turbine blade. Through the comparison of the temperature and the cooling efficiency coefficient at each position of the blade under different gas inlet temperatures, the analysis results show that the inlet temperature rises from 1500 K to 2000 K, and the temperature of the blade surface can always be kept below 1550 K,and the distribution of the blade surface temperature will be more uniform. But the overall cooling efficiency will decrease, and the temperature difference between the pressure side and the suction side will gradually increase in a small amount.
Aiming at the influence of different burial depths and different flow rates on the thermal interference of the soil around the buried pipe, a line heat source model of the vertical buried pipe heat exchanger is established. The effect of the buried pipe on the surrounding soil temperature was calculated and analyzed at four drilling depths of 40, 60, 80,and 100 m; and the impact of the buried pipe on the ground pipe at four flow rates of 0.75, 1.25, 1.75, and 2.25 m/s at each depth was studied. The effect of heat exchange and surrounding soil temperature. The results show that the buried depth of the buried pipe is negatively correlated with the soil heat-dry radius of the buried pipe, and the thermal action radius is within 6m at each buried depth. After the drilling depth reaches 80m, the effect of increasing the buried depth of the buried pipe on reducing the soil thermal interference radius is weakened. When the buried depth of the buried pipe is100, the thermal interference radius is the smallest, which is 2.3m. the inflow velocity of the buried pipe is positively correlated with the thermal interference radius of the buried pipe to the soil, and negatively correlated with the temperature difference between the inlet and outlet water. Under the burial depth of 80m, the change of flow velocity has the most obvious influence on the thermal interference radius of the buried pipe. Under the same burial depth and different flow rates, the flow rate is positively correlated with the heat transfer per unit depth and the total heat transfer.At different burial depths and the same flow rate, the flow rate is positively correlated with the total heat exchange, but negatively correlated with the heat exchange per unit depth.
TRNSYS software is used to build a system model, with the system life cycle economic cost as the objective function, and the Hooke-Jeeves algorithm is called to ensure that the indoor temperature reaches heating during the heating season. Under the premise of requirements, the four key parameters of hot water storage tank volume, solar collector area, biomass boiler rated thermal power, and solar collector inclination angle are optimized. The results show that the solar energy guarantee rate of the optimized combined system is 27.5%, the ratio of the water tank volume to the solar collector area is 101 L/m~2, best collector inclination angle is φ+18°（φ is the local latitude）, the biomass The rated thermal power of the boiler is 1.27 times the instantaneous maximum thermal load of the building during the heating period, and the economic cost of the optimized system life cycle is reduced by 17.8%. The influence of the rated heating power of the biomass boiler, the area of the solar collector, the volume of the hot water storage tank, and the inclination of the solar collector on the economic cost of the life cycle of the system is successively reduced. The research results can provide reference for the design and application of the combined system.
Based on the analysis of the design status of the air-conditioning chilled water system in the personnel access plant of Karachi K-2/K-3 nuclear power project, the corresponding improvement measures are summarized. It provides different design ideas for the subsequent personnel access plant of nuclear island or other similar air-conditioning chilled water system.
Compared with the traditional atrium, an atrium of the high-rise building has some unique features, which include an obvious vertical temperature stratification, chimney effect, massive infiltration air and so on. Combined with a super high-rise building, this paper studied on the thermal environment, by measuring the temperature distribution of atrium, and simulating indoor thermal environment with CFD simulation. With the aims to analyze the influence of air supply angle of stratified air conditioning and infiltration air volume of shuttle elevator on the thermal environment, it provides references for the design of air conditioning system of super high-rise atrium.
This paper developed a heat transfer model of radiant floor by considering the downward heat transfer through insulation layer. The analysis solution can be obtained by using the method of variable separation on the model with the assumption of an adiabatic plane in the floor. Numerical simulation for this floor by Fluent was also conducted for the benchmark of analysis solution assessment. The results show the calculated surface temperature and heat flux by the analysis solution without considering the heat transfer through insulation layer differ from the simulation results significantly. However, the calculated surface temperature and heat flux by the analysis solution with considering the heat transfer through insulation layer agree well with the simulation results. The average surface temperature error is0.22 ℃, and the relative average error of heat flux is 3.2%.
Radiant floor cooling, radiant ceiling panel cooling and fan-coil unit’s cooling experiments were respectively conducted by air-cooled heat pump. As for the three terminal systems, difference indoor temperature in the three systems after starting and stopping the heat pump was analyzed, the start-up time and energy storage capacity among the three terminal devices were described.The experimental date showed that radiant floor cooling had the longest start-up time,but it had the biggest energy storage capacity, so that it can maintain to offer cooling during the following hours. But also horizontal temperature field distributed evenly, the temperature vertical gradient is very small in the systems of both radiant floor and ceiling panel cooling.
Critical velocity is very important to smoke control in longitudinally ventilated subway tunnel fires. When the metro train is in the subway tunnel, the ventilation flow is accelerated in the block region due to conservation of mass.Hot smoke validation experiment and grid sensitivity analysis were conducted to ensure the accuracy of numerical simulation results. Numerical simulations were carried out to respectively study the effects of train blockage ratio and train blockage length on critical velocity in subway tunnel fires. Results show that train blockage length has no significant influence on critical velocity in subway tunnel fires. Critical velocity in subway tunnel fires with train blockage is higher than that of subway tunnel fires without train blockage. With the increase of train blockage ratios, the critical velocities of subway tunnel fires decrease. There is a linear relationship between the increase rate of train blockage ratios and the decrease rate of critical velocities in subway tunnel fires. Finally, according to the results of theoretical analysis and numerical simulations, a modified critical ventilation velocity prediction model including the factors of blockage ratio is proposed for subway tunnels with train blockage.
This paper takes the comprehensive teaching buildings of universities in severe cold area C as the research object, and uses on-site research methods to obtain the thermal environment parameters of each space area and indoor personnel vote for areas such as closed large spaces, closed small spaces, semi-open spaces, and transitional spaces. The results show that: the thermal environment comfort degree voting is different by the heating feeling and the wet feeling.The closed small space has the highest thermal environment comfort evaluation, and the transitional space has the lowest evaluation; the TSV model shows that personnel in the transitional space are sensitive to the temperature. The ability to adapt to changes is the strongest, and the sensitivity to temperature changes is the lowest. There are differences for the actual thermal neutral temperature in these areas, which are 17.83, 19.18, 16.28, 15.86 ℃. Orthogonal experiments on the factors affecting human thermal comfort show that closed large space and semi-open space are significantly affected by the thermal resistance of clothing, and closed small space and transitional space are significantly affected by air temperature.
The thermal storage characteristics of phase-change thermal storage electric heating module was researched through experiment and numerical simulation.The analysis of the influence of electric heat source power, module thickness and phase change temperature on the Indoor side surface temperature, heat flow density and stable heat storage cycle can guide the reasonable design and practical application of phase change thermal storage electric heating module.
The outdoor ambient temperature and solar radiation have a great influence on the thermal environment in the tent. Several tent structures with different thermal insulation materials are designed and manufactured, and the temperature difference in the tent is compared and analyzed. The results show that the air temperature and internal surface temperature of tent was decreased to a certain extent for the tent with aerogel thermal insulation, which has an obvious thermal insulation effect and can effectively improve the internal thermal environment. The phenomenon of "solar over temperature" caused by the sun exposure has been effectively improved. However, the indoor environmental temperature of the tent is still high. The tent can still be uninhabitable without air conditioning and refrigeration equipment.
Based on the characteristics of air conditioning load in hot summer and cold winter areas and the actual use of the stadium, the design idea of using a composite system for the cold and heat sources of the stadium is proposed.Taking Nantaihu Wetland Olympic Park Stadium as an example, the design of the composite system composed of ground source VRF air conditioning system and air-cooled VRF air conditioning system is introduced in detail, and the design of outdoor underground pipe system is introduced and discussed.
This paper is based on the combustor of a boiler with a rated evaporation capacity of 10t/h.Numerical simulation of different operating conditions of natural gas burners with CFX19.0.Mainly adopted standard k-ε model,Finite rate Chemistry and eddy dissipation model（FR/EDM） and P1 radiation model to simulate the internal details of the furnace. Take different excess air coefficients as variables,analyze the temperature distribution,oxygen consumption and nitrogen oxide（NOX） generation under different excess air coefficients. The results show that when the excess air coefficient is α=0.99, α=1.15 and α=1.23, the highest temperature of the furnace center reaches 2030K、2100K and2070K, respectively. As the excess air coefficient increases, the combustion temperature first increases and then decreases, and the nitrogen oxide emission concentration changes with the temperature trend. When the excess air coefficient is 0.99, the nitrogen oxide emission reaches 68.63 mg/m~3,which satisfies low-nitrogen combustion.
The effective operation of the smoke exhausting system of corridor in Public Buildings is essential for the safe evacuation of personnel in the case of a fire. The corridor layout of some large buildings is relatively complicated.For example, the width of the corridor is inconsistent, and the shape is irregular. Therefore, smoke exhausting system design of corridor is becoming more and more difficult. This paper focuses on the analysis of the calculation method of the length of the long side of the corridor, the influence of the increase of the local width of the corridor on the smoke exhausting system and the natural smoke exhaust from the corridor, and give specific solutions accordingly. Finally,taking a practical project as an example, combined with the above problems, the specific design scheme of smoke exhausting system is introduced.
In order to solve the poor refrigeration effect and high energy consumption of the refrigeration system of a station building, a series of modifications were carried out. Based on the analysis of the actual operation of the reformed system, the energy-saving optimization control strategy of different types of refrigeration units was discussed. Finally, the energy-saving effect of the same operation cycle in the refrigeration season was analyzed. The results show that the energy consumption after the system transformation is lower than that in the same period before the transformation.
Taking a data center of Wuxi Innovation Park as an example, this paper introduces the test method and test contents in detail to examine the actual temperature and humidity of the room. The results of the test data are compared with the standard, the problems in the test are analyzed, and the improvement measures and summary are put forwarded.It provides reference for the construction, energy saving and reasonable operation of data center.
After the implementation of 《Technical standard for smoke management systems in buildings》GB51251,it puts forward higher requirements for the division of smoke control zones. Aiming at the smoke control and exhaust design problems encountered in architectural engineering design, this paper analyzes the relevant provisions of the current national specifications on the setting of draft curtain, analyzes the setting position, height, length and installation mode of draft curtain, and puts forward personal opinions combined with examples.
The requirements of relevant specifications and literatures on the plane layout and pressure gradient of positive and negative pressure switching operating room have been introduced, the ventilation and air conditioning system schematic diagram of some positive and negative pressure switching operating rooms have been analyzed, it was pointed out that there were some problems. The idea that there is no return air when the negative pressure condition of ventilation and air conditioning system in positive and negative pressure switching operating room has been put forward.And according to this idea, the design of ventilation and air conditioning system and automatic control system of positive and negative pressure switching operating room have been discussed,and the schematic diagrams have been given.
