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Due to the complexity and variety of textures on Strip steel, it is very difficult to detect defects on rigid surfaces. This paper proposes a metal surface defect classification method based on an improved bat algorithm to optimize BP neural network. First, this paper uses the Local Binary Pattern(LBP) algorithm to extract features from six types of defect images including inclusion, patches, crazing, pitted, rolled-in, and scratches, and build a feature sample library with the extracted feature values. Then, the WG-BA-BP network is used to classify the defect images with different characteristics. The weighted experience factor added by the network can control the flight speed of the bat according to the number of iterations and the change of the fitness function. And the gamma distribution is added in the process of calculating loudness, which enhances the local searchability. The BP network optimized by this method has higher accuracy. Finally, to verify the effectiveness of the method, this article introduces the five evaluation indicators of accuracy, precision, sensitivity, specificity, and F1 value under the multi-class model. To prove that this algorithm is more feasible and effective compared with other swarm intelligence algorithms. The best prediction performance of WG-BA-BP is 0.010905, and the accuracy rate can reach 0.9737.

The improvement performance of refrigerating dehumidification system was theoretically discusses based on a dehumidification model. The influence of evaporator inlet wind speed, dry bulb temperature and relative humidity on dehumidification were analysed by the model. The results show that, when inlet air temperature and humidity were kept constant, the dehumidification capacity increased first and then decreased with increase of the wind speed. When the moisture content and the wind speed of the inlet air were kept constant, the dehumidification capacity gradually decreased with increase of the inlet air dry bulb temperature. The inlet air dry bulb temperature was between 21-36?C and the relative humidity was between 40% and 85%, the difference between the inlet air wet bulb temperature and the evaporation temperature at the optimum COP was about 10?C. There was a nearly linear relationship between the corresponding evaporation temperature at the optimal COP and the evaporation temperature with the maximum dehumidification capacity, compared with the test value, the error was less than 10%.

In recent days, the green synthesized nanomagnetic biocomposites have been evolved with tremendous potential as the future catalysts. This has encouraged us to design and synthesis of a novel Au NPs immobilized pectin modified magnetic nanoparticles (Fe3O4/Pectin/Au). It was meticulously characterized using advanced analytical techniques like FT-IR, FESEM, TEM, EDX, XPS, VSM, XRD and ICP-OES. We investigated the chemical applications of the material in the catalytic reduction of nitroarenes using N2H4.H2O as the reducing agent in the EtOH/H2O solvent without any promoters or ligands. Due to strong paramagnetism, the catalyst was easily recovered and reused in 11 cycles without considerable leaching or loss in reactivity. The green protocol involves several advantages like mild conditions, easy workup, high yields, and reusability of the catalyst. Furthermore, the desired nanocomposite was employed in biological studies like anti-oxidant assay by DPPH radical scavenging test. Subsequently, on exhibiting a good IC50 value in the DPPH assay, we extended the bio-application of the Fe3O4/Pectin/Au in the anticancer study of adenocarcinoma cells of human lungs using three cancer cell lines, PC-14, LC-2/ad and HLC-1 and a normal cell line HUVEC. The best result was accomplished in PC-14 cell lines with the lowest IC50 values.

To reduce the power consumption of the cooling system in the data center effectively, a prototype of the integrated cooling unit with rotary booster and compressor was developed, and the operating characteristics were tested comprehensively according to its cooling requirements throughout the year. A data center model reflecting the characteristics of energy consumption and environmental requirements was established, the energy consumption characteristics and influencing factors of the model data center when the integrated unit was used to meet its yearly cooling requirements in the typical climate zones in China were simulated by DeST software based on the measured characteristics of the integrated cooling unit. The results showed that compared with the traditional computer room air conditioner, the energy-saving ratio of the integrated system can be as high as 39.55% for the whole year, and the energy-saving effect is remarkable. The energy-saving potential of the integrated unit becomes more significant while the heat transfer coefficient of the envelope structure becomes larger, and the load rate of IT equipment and the annually-averaged ambient temperature lower.

To simplify the dual-loop heat pump ventilation heat recovery system, a new type of dual-cylinder rotary compressor with two independent suction ports and two independent discharge ports was designed and used to drive the heat recovery system in this paper. Thus, a system cycle approaching the Lorentz cycle was formed by dual-loop compression cycles. A test bench of heat pump system for ventilation heat recovery with a novel compressor was built to carry out system performance experiment. Experimental results showed that the COP of the dual-loop system under winter test conditions could be increased by 17.1% compared with that of the traditional heat pump system with a single loop. The COP of the dual-loop system could reach 10.21 under the outdoor temperature of −5 °C and the indoor temperature of 20 °C. Under summer test conditions, the COP of the dual-loop system was up to 33.47% higher than that of the traditional system. Under the outdoor temperature of 40 °C and the indoor temperature of 27 °C, the COP of the dual-loop independent compression system could reach 4.69. The performance level of the heat pump system for ventilation heat recovery could be greatly improved using the novel compressor with independent suction and discharge ports.

Ventilation heat recovery is an important means of effectively reducing the energy consumption of buildings. To improve the performance of a heat pump heat recovery system under large temperature difference conditions in winter, a triplex loop heat pump system, which contains three independent heat pump cycles, is proposed in place of its single loop counterpart. Operating characteristics and system performance were analyzed while indoor temperature was constant at 20 °C and as outdoor temperature dropped from 15 °C to −20 °C. Results showed that with the decrease of the outdoor temperature, the mass flow rate and temperature effectiveness of the triplex loop heat recovery system decreased whereas the heating capacity and the coefficient of performance (COP) increased. Under the experimental conditions, the COP of the triplex loop system had an advantage over the traditional heat pump system when the outdoor temperature was below 2.5 °C. When the outdoor temperature was −20 °C, the COP of the triplex system could reach 9.33, which was 23.1% higher than that of the traditional system.

It is important to cool data centers for improving IT equipment reliability through indoor temperature control. The air conditioning energy consumption is almost 38% of the total energy consumption. Free cooling in cool days is a promising technology for energy conservation. A pump-driven loop heat pipe (PLHP) system for free cooling was developed and installed in a data center project, which has a high energy efficiency ratio (EER) compared to air conditioners. The running performance of the PLHP system in the case project was tested and studied. The fitting rule of EER and outdoor temperature was obtained. The hourly energy savings and payback periods of the PLHP system for different cities of different climate regions in China were analyzed basing on the fitting formula compared to air conditioners. A national distribution map was developed to show the annual energy saving ratio in China. Results show that the PLHP system provides remarkable energy savings and the indoor temperature is remained at 18°C to 25°C. About 74.2% of Chinese cities lie in regions suitable for applications, and the annual energy saving ratio is over 30%. The average payback period for most cities in China is about 3.9 years.

In this study, a concept of air-source heat pump using heat pipes as heat radiator system (ASHPP) for room heating was proposed. The heat pipes radiator was developed to replace the heating terminal equipment used in traditional heat pump plants. A tested room with artificial load was constructed and an experimental apparatus of ASHPP system was developed. Heat radiator performances with different kinds of refrigerant and different refrigerant mass filling ratio of heat pipe have been experimentally investigated. The variations of system heating performance under the condition of different indoor air temperature and outdoor air temperature were researched. The purpose of this study is to provide technique reference for developing new heat pump room heating system.

Building energy consumption could benefit from air-to-air energy recovery ventilators. A triple-loop pump-driven heat pipe system was developed for energy recovery from exhaust air in buildings. The thermal performances of the single-loop and triple-loop systems were studied and compared experimentally under winter and summer conditions. The improvement of loop number and the uniformity of temperature difference distribution was discussed. Results indicated that heat transfer capacity and coefficient of performance increased with indoor and outdoor temperature difference, and the variation of temperature effectiveness depended on working conditions. The energy recovery performance of the triple-loop system was better than the single-loop system. The heat transfer capacity, temperature effectiveness, and coefficient of performance of the triple-loop system increased by 3.0%, 0.6%, and 56.7% in summer conditions with an indoor and outdoor temperature difference of 7.5 °C, and by 22.4%, 22.6%, and 53.5% in winter conditions with an indoor and outdoor temperature difference of 31.9 °C. The uniformity of temperature difference distribution could be improved clearly with increasing loop number in winter conditions but not obviously in summer conditions. The variation coefficient of temperature difference decreased from 17.2% to 10.2% in winter conditions, and from 4.5% to 3.9% in summer conditions.

Refrigeration and air conditioning (RAC) system Multi-evaporator structures are popularly applied in for efficient temperature and humidity control of multi-zone in underground buildings, light commercial and residential buildings, cold stores, et al., which can also attract and/or release heat from and/or to renewable sources. The increase on the system complexity makes it difficult to analyze the performance and to optimize its design and control. In this paper, a novel method, performance chart, is presented for the performance analysis and system optimization of multi-evaporator and RAC systems. The performance chart is generated by superimposing the performance curve of different evaporators of the indoor unit (IDUs), which can be applied to describe the performance of the whole RAC system by superimposing with the performance curve of outdoor units (ODUs). Based on the performance chart, the performance of multi-evaporator systems are analyzed at different conditions such as varying indoor temperatures, varying indoor air volumes, and varying IDUs’ capacities. The performance chart can give the reasonable and quantitative trends of multi-evaporator RAC system performance and guide the system design. These results showed that the performance chart can be used as a convenient tool for performance analysis and system optimization of multi-evaporator RAC systems.

A newly designed vapor-injected heat pump using injection subcooling was adopted to improve the heating performance of an R32 heat pump at cold regions. A composite test system was used to research the system working performance. Four kinds of system: single stage system (SS system), vapor injection system (VI system), vapor injection with subcooling system (VIS system) and liquid injection system (LI system) were tested and heating performance was compared with each other. The results showed that, vapor injection with subcooling can further decrease the R32 compression discharge temperature and made the system run under evaporating temperature lower to −20 °C; Heating performance was affected by the ratio of subcooling medium flow rate, and there is an optimum value for each evaporating temperature; Compared with LI system, the Coefficient of Performance (COP) of VIS system can be enhanced by 11.2%–13.6%.

This study presents a new equipment for domestic room heating, air source heat pump/heat pipe room heating system. Heat pipes used as heat radiators are connected in series and driven by condensers. The structure and design method of the new system were introduced in detail and an experimental new system was also developed. The design method was based upon the empirical formula of heat transfer and the thermal resistance of each part was comparatively analysed. The difference of saturation temperature of heat pipes and heat pump of the system were investigated experimentally in the actual test process of the prototype. The distribution characters of the heat pipe heat radiators surface temperature along the altitude direction were observed. The results demonstrated that the proposed system was capable for a long and stable operation under outdoor temperatures of −1.5 °C to 3.3 °C and indoor temperature of 20 ± 1 °C, also the heating coefficient of performance (COP) of the ASHPP system could reach 4.35–4.64.

A pump-driven loop heat pipe (PLHP) was proposed for energy recovery from exhaust air to reduce fresh air handling energy consumption of air conditioning systems. The influences of working fluid, mass flow rate, heat exchanging area and facing air velocity on heat transfer capacity, temperature effectiveness and coefficient of performance (COP) were studied experimentally under different working conditions. The optimum working fluid and value were obtained, respectively. Results indicate that the heat transfer capacity and COP increase with the temperature difference between indoor and outdoor air while the temperature effectiveness decreases. The general performance for R32 as working fluid was better than R22 and R152a. For summer condition, the heat transfer capacity was 4.09 kW and the COP was 9.26 when the mass flow rate was 250 kg h−1, the heat exchanging area was 58.0 m2 and the facing air velocity was 1.8 m s−1. For winter condition, the heat transfer capacity was 6.63 kW and the COP was 14.20 while the mass flow rate was 300 kg h−1, the heat exchanging area was 58.0 m2 and the facing air velocity was 1.8 m s−1. The tested device could meet the energy recovery need with remarkable energy savings.

Data centers must be cooled appropriately through indoor temperature control in order to improve information technology (IT) equipment reliability. Free cooling is a promising technology for energy conservation in data centers. A miniature pump-driven loop heat pipe (PLHP) unit for free cooling is developed for a small data center. The unit consumes low power and has a high energy efficiency ratio (EER) compared with air conditioners. The operating performance of the PLHP unit installed in the case data center in Beijing was tested and studied. The EERs under different outdoor temperatures were analyzed, and the fitting variation rules were obtained. Compared with air conditioners, the annual energy savings of the PLHP unit for both hours and days were tested and analyzed based on the fitting formula. Results show that indoor temperature is maintained at 18–25 °C, and that the test energy saving ratio is over 20.18%. Hence, the PLHP unit can replace air conditioners for cooling the case data center.

Highlights • Ultrasonic-assisted thawing was applied to the thawing process of frozen white yak meat. • Ultrasound-assisted thawing can shorten the thawing time of frozen white yak meat. • Ultrasound-assisted thawing retains the qualities and nutritionals of white yak meat. • The 400 W is the appropriate ultrasonic power for thawing frozen white yak meat., The objective of this study was to assess the effects of ultrasound-assisted thawing (UAT) on the quality of longissimus dorsi muscles from white yak meat (WYM). Ultrasonic power levels of 0, 200, 400, and 600 W (frequency of 20 kHz) were used to assist thawing. The thawing rate, meat quality, nutrient substances, volatile compounds, and microstructure of the WYM were determined. The results showed that ultrasonic thawing treatment reduced thawing times by 30.95–64.28% compared to control. The meat quality results revealed that the thawing loss, cooking loss, L* and b* values, and pH values decreased significantly while the a* value and cutting force increased significantly (P

The energy consumption of data centers is increasing rapidly with the development of technology. In order to reduce the energy consumption, free cooling technology instead of the conventional refrigeration system is feasible in the cold season. In the present work, a pump-driven two phase cooling system which is an excellent free cooling technology was developed and the prototype was investigated experimentally. The experimental results show that the efficiency of the magnetic pump was 7.7% at the motor frequency of 22 Hz, the cooling capacity of the system was able to reach 3.429 kW and 9.241 kW when the temperature differences between indoor and outdoor were 10 °C and 25 °C, respectively, and the EER were 12.9 and 29.7, which are extremely higher than the conventional refrigeration system.

The performance of heat pump ventilation heat recovery system can be effectively improved using multiple-loop independent compression cycle. The influence of the DR change on the performance of dual-loop system was predicted through calculation to explore the influence of the change in displacement ratio (DR) on the performance of the system and the direction of further improving the performance of the system. The optimum DR in dual-loop system was calculated. The performance differences of two dual-loop heat pump systems with different DR values were compared by experiments. Results show that the optimum DR is between 0.8040 and 0.9206, and this optimum DR maximizes the COP of the system. Experimental results show that, compared with the COP of the system with the DR of 2, that of the system with the DR of 0.5 can be increased by 14.8%. Compared with the overall COP of the triplex loop system with the same displacement in each loop, that of the system with the DR of 0.5 is even higher under certain test conditions. The comparison results of COP changes are in accordance with the prediction of simulation calculation. Therefore, a reasonable increase in the displacement of the low-pressure loop in the multi-loop heat recovery heat pump system will improve the system performance.

An all-year cooling system integrated with a rotary booster and a compressor was developed to reduce the energy consumption of data-com center, and the experimental setup for the prototype was established. The prototype of the integrated cooling system, which was running with the compressor in the throttling (CT) mode and the rotary booster in the throttling (BT) or non-throttled (BN) mode, was experimented comprehensively. Results show that when the difference between indoor and outdoor temperatures (Δt) is 25 °C, the maximum Q and energy efficiency ratio (EER) of the system running in BT mode are 18.58 kW and 14.66, respectively. The EER of the system running in BT mode becomes smaller than that of the system in BN mode when Δt is 15 °C. To meet the cooling requirements, the switching parameter from CT to BT mode of the system should be set to Δt = −2 °C, whereas it should be set to Δt = 25 °C when the BT mode is switched to BN mode. However, the switching parameter from BT to CT or BN mode should be set to Δt = 0 °C or 15 °C, respectively, to increase the EER.

The addition of small amounts of surfactant to water can enhance boiling heat transfer substantially. In this experiment, 2-ethylhexanol is used as the surfactant, and the critical micelle concentration (CMC) of the 2-ethylhexanol aqueous solution is determined to be 1000 mg/L. The boiling heat transfer coefficients of the solutions in different concentrations on a horizontal copper rod surface at subatmospheric pressures (1.8 kPa to 3.3 kPa) are calculated according to the experiment results. The results indicate the following: when the concentration is 500 mg/L (lower than the CMC), the boiling heat transfer can be enhanced by up to 22%; when the concentration is 1000 mg/L (equal to the CMC), enhancement is up to about 60%; when the concentration is 2000 mg/L (two times the CMC), boiling heat transfer is diminished by about 60%. To a certain extent, this experiment will guide the enhancement of evaporator heat transfer in water vapor compression refrigeration and heat pump systems.

Ventilation heat recovery devices have been increasingly used in energy-efficient buildings. Many factors, such as the attributes of buildings and the economic conditions of decision makers, should be considered in the installation of ventilation heat recovery devices. Thus, decision makers experience a multicriteria decision-making problem. This study presented a method of combining Analytical Hierarchy Process with the Technique for Order of Preference by Similarity to Ideal Solution to provide guidance in selecting ventilation heat recovery devices on the basis of the attributes of buildings and preferences of decision makers. By using residential house, small shop, and small public service center as examples, four types of ventilation heat recovery devices (total, plate sensible, integral heat pipe (R32), integral heat pipe (R717) heat exchangers) were recommended and sequenced under different background requirements through the proposed method. Results showed that the total heat exchanger obtained the highest recommended indicator value in small load application scenario, indicating its suitability. The proposed method can completely consider the attributes of buildings and psychological preferences of decision makers and combine the characteristics of different types of ventilation heat recovery devices. This approach provides scientific and reasonable recommended results in selecting heat recovery devices.

Energy consumption can be reduced effectively if ambient energy is used to cool the telecommunication base station. A thermosyphon heat exchanger was adopted as a promising technique to utilise ambient energy. A prototype was developed, and the experimental system was constructed. Relations between dimensionless entropy generation rate, heat transfer rate and energy efficiency ratio of the thermosyphon heat exchanger were discussed theoretically and experimentally. Ambient temperature and facing air velocity were also examined. Results indicated that dimensionless entropy generation rate decreased by 8-9% when temperature difference increased by 3°C and increased by 8% when the ambient temperature increased by 3°C. The errors were in the range of 5.7-14.2%. When the facing air velocity increased from 2 m/s to 3.5 m/s, the test dimensionless entropy generation rate increased from 0.4 to 0.53 and the errors were 0.53-9.56%. Simulation and test results showed similar trends under different working conditions.