Advanced Materials Research Vols. 243-249

Abstract: Capillary radiation air-conditioning is a form of high thermal comfort of new air conditioning, System's cooling capacity, surface radiation temperature and temperature distribution in air-conditioned room are important parameters to the system’s design and operation, determination and analysis of these parameters in the actual operation of capillary tube radiant air conditioning system is designed to have a practical reference value. This article is under summer conditions and through the experimental research methods, measurement and analysis the vertical, the horizontal and the wall temperature distributions of the air-conditioning room under different capillary radiation conditions, which provide reference information for the capillary tube design of the radiation air conditioning system, the selection of the operation parameters, the control of the condensation etc.

Abstract: Relative humidity is an important micro-climate parameter in radiant cooling environment. Based on the human thermal comfort model, this paper studied the effect on PMV index of relative humidity, and studied the relationship of low mean radiant temperature and relative humidity, drew the appropriate design range of indoor relative humidity for radiant cooling systems.The results show that high relative humidity can compensate for the impact on thermal comfort of low mean radiant temperature, on the premise of achieving the same thermal comfort requirements. However, because of the limited compensation range of relative humidity, together with the constraints for it due to anti-condensation of radiant terminal devices, the design range of relative humidity should not be improved, and it can still use the traditional air-conditioning design standards.

Abstract: In order to improve the performance of air source heat pump in low temperature conditions, designed a solar assisted air source heat pump with the gas-liquid bio-sources heat exchanger. The heat pump can work with solar heat water and air as a heat source at same time. The heating performance of the heat pump in low temperature conditions was tested. The results show that, in comparison to the single air source heat pump, the heating performance of the solar assisted air source heat pump is improved remarkably. When the solar water flow is at 0.6m³/h and the outdoor environment temperature is -7°C, the heating capacity raised about 38% and the COP raised about 30%. When the outdoor environment temperature is -15°C, the heating capacity and the COP all raised more than 50%.

Abstract: An improved error transfer BP neural network model is use to predict the dynamic heating load in a house or a dwelling unit with the character of hour heating load. Compared with the conventionally physical model, the computation consumption is reduced greatly for the less number of the parameters by improving the error transfer ways. The numerical simulation and experimental measure in a low energy consumption building of Dalian city are performed and the BP neural network model was based entirely on the field survey data. The results show that the simulated results are well agreed with the experimental data and the averaged relative error is less than 5%. Furthermore, this improved model can predict accurately hour heating load during the course of next 24 hours and it is favorable for predicting the short time heating load problems.

Abstract: The natural refrigerant R29O and mixed refrigerant R417A is currently approved ideal substitutes of R22, The performance of R290 and R410A in the same heat pump air conditioning water heater combination was studied experimentally, heating capacity, cooling capacity, power input, COP ,discharge pressure, suction pressure,discharge temperature were measured, the performance of heat pump air conditioning water heater combination at standard air condition and varied inlet-water temperature was analyzed .The results show that the most appropriate charge mass of R290 is only 52% of R417A in the same systems ,so using r290 more environmentally friendly.The coefficient of performance (COP) is higher than R417A in the same capacity, so using r290 have lower energy consumption, more energy-saving. Compressor discharge pressure and temperatures of R290 is lower than R417A in the same inlet-water temperature, so using r290 favors the system security operation. But the performance of R290 influenced by the inlet water temperature more obvious than R417A, it's not very suitable for the occasion of high inlet-water temperature.

Abstract: The theoretical analysis and numerical simulation for wall heat transferring process of the gas-infrared heated room is finished in this paper. The thermal equilibrium equation is established, and the heat loss is analyzed between radiant heating system and convection heating system. By means of numerical simulation, the exterior wall surface temperature distribution and the influences of wall blackness to the workspace air temperature as well as the heating energy consumption are studied.

Abstract: The gas mixing pressuring and calorific value control of gas mixing process have the characteristics of strong coupling, nonlinear, uncertainty and large time-varying. If the calorific value of mixing gas is unstable in gas pressurization station, the quality and quantity of iron and steel production will be affected. In this paper, an compound decoupling control method of fuzzy-single neuron adaptive PID is proposed according to the mixing gas pressure and calorific value decoupling control, the fuzzy decoupling controller is used to realize the initial adjustment of mixing gas and pressure, which has the characteristics of rapidity and anti-interference performance. The fine adjustment work of control process is completed by the secondary adjustment of adaptive PID controller of single neuron, the design of controller has the ability of parameter self-learning, and the simulation results show that this design scheme has a better dynamic performance than traditional PID scheme to verify the feasibility of this method.

Abstract: The heat transfer characteristic through periodical variable cross-section passage is studied with numerical scheme. The results in multi-period variable cross-section channel show that the heat transfer enhancement can be obtained by forming flow destabilization at large Reynolds number. The parameters include pressure, velocity, temperature in the channel are symmetric about central line at low Reynolds number, then change to asymmetric at high Reynolds number. The variations occur firstly at the downstream near outlet of the channel and move upstream, which could improve the fluid mixing to increase the enhancement of heat transfer in channel.

Abstract: A new type of enclosed evacuated tube solar collector integrated with building envelopes is introduced. The distinguished feature of this new device is that gaps between the evacuated tubes are filled with sheet glass and the evacuated tubes, sheet glass and edges form an enclosed cover on the building envelope. The heat loss behind this kind of solar collector is studied theoretically and experimentally and compared with conventional open evacuated solar collector. The results of research indicate that: 1) The air chamber temperature of the enclosed solar collector is rising with the increasing outside temperature and it is much higher than the outside temperature, owing to the enclosed chamber and the solar heat gain in the chamber. For the open solar collector, the air temperature behind the evacuated tubes is nearly the same as the outside temperature. 2) In the night, the heat loss of integration with the closed air chamber door is less than the open one, but the difference is not large. In the daytime, the heat loss through the building envelopes behind the enclosed solar collectors is significantly reduced with the closed air chamber doors.

Abstract: For thermal natural ventilation, buoyancy plumes deriving from heating source make thermal stratification in room. The height difference between inlet and outlet is one of the important factors influencing thermal stratification. Taking a representative civil building with inside heating sources as the research object, using the technique of CFD, changing the height difference between inlet and outlet center, this paper gives simulation on the fluid field caused from thermal natural ventilation, analyzes the velocity field and temperature field under different simulation conditions, presents the influence rule of the height difference between inlet and outlet on thermal stratification in rooms. The results can provide a theory reference for natural ventilation system design in domestic buildings.