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The outstanding combination of high strength, fracture toughness and low mass makes the metastable β titanium alloy an ideal material for aviation application. Machining of the metastable β titanium alloy remains a challenge due to their poor machinability. In this study, the high feed milling of a novel metastable β titanium alloy M28 is investigated to evaluate the performance of a potential high-efficiency-machining approach for the next generation titanium alloy and promote the understanding of high feed milling. The cutting force and the wear mechanism of carbide tool coated with TiAlN-Al2O3 are investigated as well as the influence of high feed on machined surface microstructures and microhardness. Due to the chip thinning effect of high feed milling, a proper high feed maintains a sufficient chip thickness to prevent the ploughing. Cutting edge degeneration induced by the carbide matrix fracture accelerates the tool wear. Mechanical stress induced cracks lead to the uneven delamination of the TiAlN-Al2O3 coating. Slight effect of high feed can be found on the microstructures and microhardness of the machined surface. While the tool wear leads to significant grain fragmentation and distortion at the surface. Since no white layer is found in the cutting of M28, high feed milling shows the advantage of preventing the heat induced surface injury.

The temperature of domestic drain water is relatively high, but its flux is sometimes insufficient as a heating source. Thus, the conventional wastewater source heat pump water heater is incapable of meeting user heating demand given the limited sensible heat temperature difference in many situations. To address this problem, a novel in–house heat pump water heater with a freezing latent heat evaporator and assisted by domestic drain water was proposed. A prototype of the system was first constructed to determine the performance of the system. An experiment was then conducted, in which a parallel helical coil tube evaporator was designed and developed to extract freezing latent heat from domestic drain water. Experimental data was obtained in different experimental conditions. Results of the investigation show that the heat pump water heater with a freezing latent evaporator recovers 3.4 times more energy than the conventional wastewater source heat pump water heater, and saves 60% energy compared with the traditional electric water heater. Furthermore, an interesting result is that the heat transfer coefficient increased significantly at the moment the wastewater was just frozen. This paper provides a reference for the wastewater source heat pump water heater to extract freezing latent heat from domestic drain water.

Among sub-items of energy consumption in public buildings, lighting sockets play an important role in energy-saving analysis. So, the energy consumption data quality of lighting sockets is important. However, limited by the initial cost of energy monitoring platform, it is difficult to install electricity meters covering all branches and to retrofit the incompact classification electricity branches, which results in a mixture of the lighting socket energy consumption and other components. In this study, a separation methodology is proposed. First, the abnormal data in the energy monitoring platform are cleaned and screened using a clustering algorithm. Second, the average outdoor air temperature partitioning model (OATPM) method and the k-nearest neighbor (KNN) clustering algorithm method are proposed for identifying and separating the abnormal data. These two methods have complementary advantages in the best applicable scenarios, including calculation accuracy and other aspects. The verification results for three buildings show that the relative error of this separation methodology is less than 15%. Finally, this paper presents the optimization parameters of the KNN method. Through this methodology, building managers need only historical data in an energy monitoring platform to separate the combined power consumption of the lighting sockets and air-conditioning online, independent of detailed information statistics.

An intensive study on the heating temperature aimed to create a satisfying indoor condition that should meet the residents’ thermal requirements in accordance to their daily behavior pattern. Unlike urban residents who stay indoors for a long time, rural residents constantly live in a dynamic environment: they often leave their residences and get busy with numerous labor activities. Therefore, the thermal sensation questionnaire survey performed in a steady environment is not suitable for them. To study the rural heating temperature in a dynamic environment, a three-years field investigation was performed in South Liaoning province. During the investigation, a continuous tracking method was adopted to record the residents’ behavior; objective environmental parameters test and subjective thermal sensation surveys were rigorously recorded. The results indicate that the residents behavior pattern exerts an influence on the heating temperature by influencing the residents’ clothing insulation. Heating temperature in auxiliary rooms can be directly determined by the residents’ thermal sensation, with the reasonable value of 11 °C. The influence of residents’ behavior on clothing should be considered when determining heating temperature in the master bedroom, the reported value of which is 13 °C. The heating temperature obtained by the thermal sensation fuzzy comprehensive evaluation model in paper reflects the rural residents’ real-life requirements on thermal environment, and it provides a reference for designing rural residences.

The main objective of the present study is to investigate the heat transfer characteristics of vertical falling film evaporation of refrigerant R-134a outside of a single smooth and enhanced tubes. The experiment was carried out under the conditions that spray density in the range of 0.058–0.44 kg m−1 s−1, corresponding inlet Reynolds number from 1000 to 6800. The evaporation temperature ranges from 6 to 12 °C and heat flux is between 10 to 40 kW m−2. Variations of heat flux, spray density and saturation temperature were analyzed. The obtained results revealed that the saturation temperature has little influence on enhanced tube, but it can improve the performance of the smooth tube markedly. Moreover, it was found that as the heat flux increases, the heat transfer coefficient of the smooth tube increases, while that of the enhanced tube significantly reduces. Nevertheless, the heat transfer performance of the enhanced tube still outperforms that of the smooth tube up to 2∼12 times. Besides, it was also found that spray density is an important factor for vertical falling film evaporation. The increase of the spray density appropriately can improve the heat transfer coefficients in both smooth and enhanced tubes, but the supply that is too much or too little both has adverse effects. Accordingly, the spray density should be kept in a optimum range, especially the minimum must be reached in order to prevent liquid film break and the dry-out patch. The present study provides a basis to investigate the application of enhanced tube in the vertical falling film evaporator.

Electricity consumption in university dormitories deserves more attention owing to its constituting a large proportion of total electricity consumption in university buildings and the enormous electricity conservation potential. This research proposes a methodology comprising aggregated and segmented analyses to provide an in-depth understanding of electricity consumption in university dormitories from multiple perspectives. Aggregated analysis provides global perspectives for electricity consumption by resolving a novel and practical problem of setting free electricity consumption quotas for student dormitories. Segmented analysis provides partial perspectives for electricity consumption by discovering electricity consumption patterns according to the academic calendar. The actual daily electricity consumption data of 2434 undergraduate dormitories, 542 graduate-MS dormitories, and 583 graduate-PhD dormitories collected by smart meters from a Chinese university are analyzed to demonstrate the application of the proposed methodology. The main results of the research include the following: (1) different modes of setting free electricity consumption quotas have different effects on electricity conservation, and the monthly mode seems to be a more efficient alternative to stimulate energy-saving behaviors than the annual mode; (2) there is no significant linear correlation between outside temperature and electricity consumption against the background of limited electric power and nonusage of air conditioning systems; and (3) the representative electricity consumption patterns in the three types of dormitories are explored according to the academic calendar. The university administrators can devise good electricity use policies and implement electricity network planning and operations according to the patterns. The implications of the results and several recommendations for promoting energy conservation are provided simultaneously

Super-long urban road tunnels have become prevalent in China recently. This study established a three-dimension CFD model containing two adjacent super-long urban road tunnels to estimate characteristics of pollution dispersion outside the tunnels. The results indicated that crossflow between two adjacent tunnels was quite severe, which contributed to carbon monoxide concentration was almost 50 ppm exceeding the 10 ppm limit of National Standard in China for 1h exposure level when exhaust shafts were absent. When the shafts exhausted 80% pollutants from the tunnel portal, crossflow between two adjacent tunnels could at least decrease to 20% of the conditions without shafts. The simulation results could not only demonstrate the importance of shafts for super-long urban road tunnels, but also provide a fundamental and guideline for evaluation of urban environment and design of the tunnel exhaust shafts, including locations and types.

Generally, the temperature of domestic waste water is high above 30℃. However, when dealt with by common sewage-source heat pump system, temperature difference between inlet side and outlet side is small as 5℃. It leads to manifold cycles and energy waste. To acquire a unit of heat pump water heater of sewage dealing with large temperature difference with high energy utilization rate, through which the cold water (about 5℃) can be heated once to hot water (about 45℃) to reach the temperature for daily use and waste water (about 30℃) can be rapidly dropped to cold water (about 6℃) to satisfy the standard of waste water emissions. In this paper, two staged series of heat pump water heater dealing with large temperature difference is proposed. And performance factor of system is analyzed through simulation by MATLAB so as to find the optimum middle operating point. This method ensures pattern operating in large temperature difference but in small flow at both the hot and cold sides. At the same time, it avoids the lasting elevation of condensing temperature and the constant reduction of temperature in evaporation, which helps to facilitate the stability and optimal performance of the operating unit.

In this paper, a heat pump hot water unit with the dual-source evaporator using air or water as the heat source is proposed. The idea is firstly to use the heat from the bath wastewater to heat the domestic hot water. If the stored wastewater is insufficient, the ambient air will be applied for assisting the heat pump. The structure of the dual-source evaporator is simpler and compacter compared with the traditional form of two evaporators arranged in parallel. For testing it, the heat pump hot water unit with the evaporator is established. The performance of the unit and the dual-source evaporator are investigated experimentally when the bath wastewater is used as the heat source. Experimental results show that the coefficient of performance (COP) of the heat pump can reach 5.02 when the wastewater temperature is 32℃, and the heat transfer coefficient of the evaporator can reach to 1003.56 W/m2 K. And the temperature of wastewater can be decreased to 8℃ by cyclical utilization. So the effect of heat recovery is remarkable for the heat pump hot water unit with the dual-source evaporator. When air is used as the only heat source, the performance of the heat pump is about the same as that of a conventional air-source heat pump, and this paper does not research on it.

Heat pumps are a part of the environmentally friendly technologies using renewable energy and have been utilized in HVAC systems. A heat pump water heater unit with frozen type evaporator was designed and developed. And a test bed was constructed to determine the performance of the unit. In the experiment, a parallel helical coil type evaporator was used in the unit to extract latent heat from the sewage. The data (dynamic COP and other parameters) was obtained in three processes(including the first freezing, melting, and the second freezing) at different water temperatures (8.2℃ and 13.8℃). Results show that compare with traditional water source heat pumps, the newly designed unit with the frozen evaporator can reduce the required water amounts as a heat source by more than 90%. The higher initial temperature of hot water and sewage, the higher temperature of sewage after melting. Meanwhile, with the increase of the initial temperature of hot water and sewage, the comprehensive COP was greater. This paper will provide a reference for the sewage source heat pump system to extract the latent heat from the sewage.

Targeting at rural residence in south Liaoning province, a continuous test on indoor temperature and atmospheric temperature is made and a questionnaire survey about residents’ thermal sense is conducted. Combined with local residents’ mode of life, living habit, psychological demand, economic situation and so on, heating design temperature of south Liaoning province is given. It shows that the temperature demand of residents that live in traditional house is lower, which of master bedroom is 12 to 14 centigrade. To newly building, the heating temperature demands of different rooms are different. The heating design temperature of frequently used room ranges from 12 to 14centigrade, and occasionally used room ranges from 10 to 14 centigrade. However the heating design temperature of room which is hardly used is from 9 to 13 centigrade. This paper will offer theoretical basis for new rural construction in south Liaoning province.

In order to increase the efficiency of solar collector, a methodology is proposed based on the analysis of its influencing factors, such as thermal conductivity of filled layer, structure forms of filled layer and heat loss coefficient. The results of analysis show that the heat transfer between pipes in evacuated tube is one of the most important factors, which can lead to the decrease of the outlet temperature of working fluid. In order to eliminate the negative influence of the heat transfer between pipes, the hollow filled-type evacuated tube with U-tube (HUFET) was developed, and the heat transfer characteristics of HUFET were analyzed by theoretical and experimental studies. The results show that the thermal resistances decrease with the increase of the thermal conductivity of filled layer. When the thermal conductivity is over 10 W/(m·K), the change of thermal resistances is very little. Furthermore, the larger the thermal conductivity of filled layer, the less the rate of the energy transfer between the two pipes to the total energy transfer, which is between the absorber tube and the working fluid. There is a little difference between the efficiencies of HUFET and UFET, with the efficiency of HUFET 2.4% higher than that of UFET. Meanwhile, the validation of the model developed was confirmed by the experiment.

This paper firstly define most unfavorable thermodynamic loop to reflect the dynamic situation of terminal cooling load distribution, then present its online identification method that can easily applied for optimal reset of differential pressure. We use the optimal domain of maximum valve position among whole braches in chilled water system to calculate the variation of differential pressure setpoint, and control the pumps according to the optimal setpoint. We applied presented method to a VWF retrofit project in a Suzhou factory building and evaluate its energy saving effect through its equipped building energy management system. Experimental results showed that presented method can achieve 22%-53% pump power consumption savings compared to traditional control method. During the test period, the average level of valve position of presented method was highest among all tested control strategies. The optimal reset method of differential pressure presented in this paper is an energy efficient, high stability and easily online applied control method.

In order to eliminate the influence of thermal resistance between the absorber tube and the copper fin of the conventional evacuated solar collector, which would decrease the thermal performance of the evacuated tube collector, a filled-typed evacuated tube with single U-tube (SUFET) was presented in our previous work, in which the filled layer was used to transfer energy absorbed by the working fluid flowing in the U-tube. In this paper an improved filled-type evacuated tube with double U-tubes (DUFET) was presented by means of theoretical analysis and experimental study to increase the heat transfer area and then improve the heat transfer efficiency of collectors. The structure of filled-type evacuated tube with double U-tubes was given first, and then the thermal performance of filled-type evacuated tube with double U-tubes was studied in both theory and experiment. The experimental results showed the feasibility and validity of this design. Finally, a comparative study between SUFET and DUFET was given at the same working conditions.

Through the integrated modeling of gas turbine and tunnel kiln combined system, a thermodynamic calculation method of combined system is put forward, and the combined system operation parameters are obtained. By this method, the optimization of the combined system is analyzed and the optimal configuration of the gas turbine is calculated. At the same time, the thermal efficiency of the combined system is analyzed, and the heat distribution and thermal efficiency of the system before and after the improvement are explained. Taking the 1500 kg/h ceramic production as an example, pointed out that if the tunnel kiln has a gas turbine with a power of 342 kw. The amount of electricity of the combined system that produced per unit volume of the fuel which consumes more than it used to will be 7.19 kwh, the system thermal efficiency will reach 57.49%, which higher than the individual gas turbine's cycle thermal efficiency 20% at least.

Owing to the cold and windy weather in southern Liaoning province in winter, the heat loss through doors and windows accounts for 20 to 30 percentage of the whole heat loss of house. To decline the heat loss through doors and windows, focusing on the typical rural house, an energy consumption system is built. On the basis of it, a study about the influence on the indoor temperature of windows’ heat transfer coefficient, airtightness, size and the outside door is made. The results show that on the condition of the same heat supply, the temperature of the room, which installs single frame double glass windows, is 2 centigrade higher than which installs single frame single glass windows, and is 0.4 centigrade higher than which installs double frames single glass windows. The indoor temperature of room installing casement windows is 0.5 centigrade higher than the room installing sash windows. For the southern window, the heat flowing into the house is more than the heat losing through window, and the bigger the window, the higher the indoor temperature. However, regarding there is no direct solar radiation in the north, for the size of northern window, the little, the better. In rural house, the foyer can prevent cold air from flowing into the rooms directly. In other words, there is a temperature buffer around rooms. The simulation results show that the existence of foyer can raise the temperature of kitchen 1.1 centigrade. The study of this paper will offer theoretical basis to the new countryside construction.