Advanced Materials Research Vols. 960-961

Abstract: Three different structural types of closed cooling tower (CCT) and two cooling water flow directions were considered. The experimental study were done on the cooling performance of influences of inlet air dry and wet bulb temperature, cooling water flow rate and inlet temperature, air flow rate and spray density. The experimental results show that the cooling performance of CCT with packing is obviously better than non-packing cooling tower in 7%~18.4%. And the cooling performance of CCT with packing on top and coil underneath is slightly better than CCT with coil on top and packing underneath in 4.9%. In the same conditions the cooling performance of CCT with packing under cooling water cocurrent-flow is better than that cooling water countercurrent-flow in 3.2%~9.6%. Therefore, the closed cooling tower structure with the cooling water path in bottom and out top, and with packing on top and coil underneath is recommended.

Abstract: The optimized air measuring station location of mine airway based on air fully developed was proposed and numerical tests were conducted with six models. The independence of air fully development and inlet velocity was analyzed which validated the models and the numerical methods. The results show that optimized air measuring station location in head entry is 132m-198m after the airway turning while 5.0m-10.1m before the airway turning in tail entry.

Abstract: The air conditioning system did not run as the design conditions in most of the time. Therefore, how to rationally adjust air parameters under part-load conditions caused by changes in the outdoor environment is an important issue, which is crucial to people’s comfort and energy systems. This paper introduces the part-load rate α to distinguish among different load-part conditions. And by taking the typical conditioned space of underfloor air distribution (UFAD) system in perimeter zone of New Tianjin Library as the object and using Fluent for simulation analysis, we get the conclusion that there is a maximum limit of supply air temperature and a minimum limit of supply air velocity under summer part-load conditions. For each condition, there is a set of optimal air parameters to make the indoor personnel achieve the most comfortable condition. Finally, we acquire this set of optimal air parameters by simulating and analyzing.

Abstract: With the fast development of superconducting, nuclear-energy and high-energy physics, further requirement of the system of large-scale helium refrigeration is brought forward by some associated subjects. The present controlling system of the system abovementioned is not well able to deal with the interruption such as the heat pulse impact. Thus, it leads to a new challenge that must be confronted with by the system of large-scale helium refrigeration.This paper aims at the control of gas management panel (GMP) in compression station of large-scale helium refrigerator. The neural network PID control of GMP in the system is introduced and simulated.

Abstract: More and more attentions have been paid on ice-storage low temperature air supply system because of its notable energy saving effects and comfort. The paper expatiate on that ice-storage low temperature air supply system brings a series of especial superiority to modern air-condition cause. The results show that low temperature air supply system can exert the potential advantage of ice-storage further. The combination of ice-storage and low temperature air supply system can obtain an “integrated approach”, which can save energy resources and improve human body comfort and indoor air quality.

Abstract: In this paper, microcontroller is applied in the central air conditioning control system. Firstly, microcontroller controller is used as controlling core to control temperature and humidity of central air conditioning control system. Secondly, PID algorithm parameters are set up for improving traditional PID control principle. Lastly, input and output values can be set and displayed by LCD screen.

Abstract: A stepped capillary tube consisting of two serially connected capillary tubes with different diameters is invented to replace the conventional expansion device. The mass flow rate of refrigerant R410A in stepped capillary tubes with different size were tested. The model of stepped capillary tube is proposed, and its numerical algorithm for tube length and mass flow rate is developed. The experimental results show that the performance comparing between stepped capillary tube system and capillary tube assembly system, the cooling capacity is reduced by 0.3%, the energy efficiency ratio (EER) is equal to each other, the heating capacity is increased by 0.3%, the coefficient of performance (COP) is decreased by 0.3%. That is to say, the performance index of the two kinds of throttle mechanism is almost identical. It indicates that the stepped capillary tube can replace the capillary tube assembly in the R410A heat pump type air conditioner absolutely. The model is validated with experimental data, and the results show that the model can be used for sizing and rating stepped capillary tube.

Abstract: In order to calculate the structure size of stepped capillary tube, the experiments of flow characteristic of it were performed. The experience benchmark model of flow characteristics of R22 was set up through experimental method in specific reference conditions based on the impedance calculation method. The variable working condition model suitable for a range of conditions was obtained through fixing the condition based on the reference model. The mass flow rate of refrigerant R22 in two stepped capillary tubes with different size was tested. The experimental results show that the stepped capillary tube model has a high precision and working condition of certain flexibility. The deviation of cooling and heating flow between the calculated values and measured values are less than±10%. The model can meet the need of matching for stepped capillary tube on the heat pump type air conditioner with R22.

Abstract: Gas Load Characteristics of different users are analyzed in this paper. Different types of load charts which is drawn according to the statistical data may provide certain guidance for gas companies. Non-uniform coefficient method that continues to be used for calculation of gas load in China has limitations. It is more reasonable to calculate gas load with load coefficient method.

Abstract: In this paper, hardware and software of the central air-conditioning control system is researched by STC series of enhanced 8051 microcontroller. The STC11F 08XE is the main control of the hardware part. Temperature and humidity sensor regulating valve and all kinds of motor are used as external equipment to complete the temperature and humidity of building the internal control of central air conditioner. In terms of software, the program is described by protel99SE software. Microcontroller program is compiled by Microcontroller development tools keil u and STC-ISP. The temperature and humidity control and optimization of central air conditioning are completed by PID parameters. Infrared control unit is operated and liquid crystal is displayed to show the operation results.