Airflow Energy Research Articles

Optimization Strategies for Underfloor Air Distribution in a Small-Scale Data Center

Abstract: The development of 5G application technology has led to a rapid expansion in the scale of internet data center rooms and the number of servers. Due to the high heat generation of data center server equipment and the mixing of hot and cold airflows within the rooms, the thermal environment of these rooms fails to meet operational requirements with increasing energy consumption and thermal density. This study utilized the 6SigmaDC software to simulate and analyze the characteristics and existing problems of airflow distribution in a small-scale data center. Based on identified issues with current airflow patterns, two optimization schemes were proposed, analyzing the effects of raised floor height and the closure of aisles on airflow optimization. The return heat index (RHI) was used as an evaluation metric to assess airflow patterns before and after optimization. When the raised floor height was 600 mm, the maximum temperature at the cabinet inlet and outlet were 19.3 °C and 34 °C respectively, which were the lowest, and the RHI value was 0.9622. Compared with unclosed aisles and closed hot aisles, closed cold aisles effectively reduced the cabinet inlet and outlet temperature and increased the RHI. In addition, closed cold aisles increased the air supply temperature from 18 °C to 20 °C, further reducing the energy consumption of the air conditioning system. This study can provide guidance and act as a reference for optimizing airflow design and energy conservation in small data centers.

Recent Patents on Long Distance Pneumatic Conveying Technology

Background: Pneumatic conveying is the use of air flow energy to transport granular materials in the direction of airflow in a closed pipeline, which involves the disadvantages of low conveying efficiency and easy deposition of particles. Objective: It is necessary to develop pneumatic conveying devices to reduce particle deposition, promote particles to enter the flow field again to accelerate, and achieve the effect of extending the pneumatic conveying distance. Method: The anti-settling device re-accelerates the particles so that the particles return to the flow field, which effectively reduces the probability of settlement blockage of material particles during transportation. The pneumatic conveying pressurized separator uses a pot-shaped housing to generate an internal rotating flow field to screen particles, and the light dust adheres to the filter, reducing the possibility of pipeline dust explosion. Results: The anti-settling device can quickly replace the anti-settlement block according to the parameters of the conveying pipeline, which can effectively reduce the probability of settlement blockage of material particles during transportation. The pressurized separator can use the air compressor to cooperate with the return air pipe to effectively remove the dust in the pneumatic conveying pipe and carry out secondary pressurized transportation of the materials in the pneumatic conveying pipe, which improves the safety of pneumatic conveying. Conclusion: The above technology improves the efficiency of pneumatic conveying and gas utilization, enhances the speed of particle conveying, reduces particle settlement and collision, extends the distance of pneumatic conveying, and ensures the safety of pneumatic conveying and the feasibility of industrial applications.

Exploring the use of atmospheric freeze drying for dehydrating pharmaceutics in vials: Baseline water sublimation investigation

Atmospheric freeze-drying (AFD) is a relatively new freeze-drying technology without the need for a vacuum, making it easy to operate and cost-effective. Although there have been studies using AFD to dehydrate solid foods, there is currently no research on using AFD to dehydrate frozen liquids in pharmaceutical vials. In this study, several approaches were evaluated to enhance the atmospheric sublimation of water in pharmaceutical vials. Using −4 °C impinging jet airflow to dry frozen water samples in the vial, it was found that convective action significantly affected the sublimation rate. On this basis, a 3D-printed air-guide model was designed to improve airflow circulation in the vial, and it was found that the drying rate was highest when airflow energy loss was minimized, and airflow velocity at the sample surface was maximized. Additionally, the geometric characteristics of the vial also influenced the sublimation rate; vials with a larger bottom area and shorter height showed the highest sublimation rate. Increasing the vial’s bottom radius from 11 mm to 13 mm, under atmospheric pressure and using cold air at approximately −5 °C, reduced the drying time of 1 g of frozen water from 8.5 h to 6 h; each 5 mm height increase added 0.5 h to the drying time. Using cold air at −10 °C to dry 1 g of frozen water in a 5 mL vial, the combination of ultrasonic-induced energy (at a frequency of 39.46 kHz) and the air-guide model effectively reduced the sublimation time from 7 h to 5 h, compared to using only the air-guide model. However, this technique may be vulnerable to melting at the vial-transducer contact point, should the transducer be directly attached to the vials.

Analysis of Output Performance of Airflow Energy Harvester Using Diamagnetic Levitation Based on Taguchi Method

Analysis of Output Performance of Airflow Energy Harvester Using Diamagnetic Levitation Based on Taguchi Method

Pulsed Airstream-Driven Hierarchical Micro-Nano Pore Structured Triboelectric Nanogenerator for Wireless Self-Powered Formaldehyde Sensing.

Formaldehyde (HCHO), as a common volatile organic compound, has a serious impact on human health in the daily lives and industrial production scenarios. Given the security issue of HCHO detection and danger warning, a ZIF-8/copper foam based pulsed airstream-driven triboelectric nanogenerator (ZCP-TENG) is designed to develop the self-powered HCHO sensors. By combining contact electrification and electrostatic induction, the ZCP-TENG can be utilized for airflow energy harvesting and HCHO concentration detection. The short-circuit current and output power of the ZCP-TENG can reach 2.0 µA and 81 µW (20 ppm). With the high surface area, abundant micro-nano pores, and excellent permeation flux, the ZCP-TENGs exhibit excellent HCHO sensing response (61.3% at 100 ppm), low detection limit (≈2 ppm), and rapid response/recovery time (14/15 s), which can be served as a highly sensitive and selective HCHO sensor. By connecting an intelligent wireless alarm, the ZCP-TENGs are designed to construct a self-powered warning system to monitor and remind the HCHO of exceedance situations. Moreover, by combining a support vector machine model, the difference concentrations can be quickly identified with an average prediction accuracy of 100%. This study illustrates that ZCP-TENGs have broad application prospects and provide guidance for HCHO monitoring and danger warnings.

Micro-environment strategy for efficient cooling in telecommunication base stations

The cooling systems of telecommunication base stations (TBSs) primarily rely on room-level air conditioners. However, these systems often lead to problems such as messy airflow, hot spots, and excessive energy consumption. With the rapid development of 5G technology, the integration and power density of communication equipment continue to increase, exacerbating these problems. To address these issues, a micro-environment strategy has been developed. This strategy combines cabinet-level airflow components with unique multi-adjustable-vent air conditioners(MAVACs), which are suitable for the co-deployment of various high power density communication equipment with different airflow patterns in TBSs. An experimental study was conducted to evaluate the cooling performance of the proposed MAVAC, and CFD simulation was carried out to investigate the temperature distribution and airflow patterns using a typical TBS in China that has implemented the micro-environment strategy. The results demonstrate that the micro-environment strategy effectively separates the cold air and hot air, preventing the occurrence of hot spots. The maximum return air temperature of MAVACs was found to be 38.6℃. Additionally, the energy efficiency ratio of the MAVAC system increases by approximately 20 % when the return air temperature is raised from 35℃ to 40℃. This study is expected to contribute to energy savings in TBSs and the successful construction of 5G networks.

Research on the cooling mechanism of low-temperature liquid jet mixing in high-temperature and high-speed airflow

The multi-stage water spray cooling system of the space launch site involves a complex gas–liquid two-phase mixed cooling problem in the process of spraying water onto the rocket engine gas jet. To investigate the complex multiphase flow field of the interaction between the airflow and liquid water jet, the Mixture multiphase flow model is adopted, which is coupled with the vaporization equation and component transport model of liquid water. The computational fluid dynamics method is used to numerically analyze the mixing and cooling mechanism of low-temperature liquid jet in high-temperature and high-speed gas flow. The results show that mixing low-temperature liquid jets in high-temperature and high-speed airflow can cause the exchange of momentum and energy, resulting in pressure loss and temperature reduction in the gas phase flow field. Due to the acceleration of transverse airflow, the diffusion flow range of the jet is significantly increased, and violent vaporization occurs, which further consume a large amount of airflow energy. The mixing cooling effect of transverse airflow and liquid water jet is directly related to the mass flow rate ratio of the jet to airflow. In addition, directly designing liquid water jet orifices on the solid wall of the guiding device can achieve the effect of improving the gas flow field environment. This conclusion can provide theoretical reference for the thermal protection design of ground launch devices in space launch site.

A fast wide-range air balancing control method based on deep reinforcement learning

Air balancing is a crucial technology for reducing energy consumption in ventilation ducts and improving indoor environmental quality. Existing air balancing methods face challenges due to the complex and diverse internal duct topologies of ventilation duct systems, as well as the strong coupling of airflow between branches, making air balancing tuning difficult. To address the slow convergence speed and difficulty in precise control of air balancing in multi-branch ventilation systems, this paper proposes a fast wide-range air balancing control method based on deep reinforcement learning (DRL-AB). A system airflow control process with Markovian properties is designed, with state, action, and reward functions oriented towards reducing airflow errors. A dynamic single-branch target training mechanism is designed to reduce training costs while improving the agent’s training efficiency and its ability to generalize to different target airflow levels. The proposed method’s performance under various target airflow conditions is verified through experimental platforms. The results indicate that, in all test cases, the maximum percentage error is controlled within 3.33%, ensuring rapid and accurate convergence of a wide range of target airflows. This demonstrates strong universality, prevents waste of airflow energy, and enhances energy utilization efficiency.

Energy Harnessing Performance of Oscillating Foil Submerged in the Wake of a Fixed Cylinder

The energy harnessing from flow-induced vibrations (FIV) by an oscillating foil placed tandemly behind a circular cylinder (which serves as a vortex generator) is investigated. The foil is submerged in the wake produced by the fixed cylinder and could oscillate in the direction perpendicular to the incoming flow with single-degree freedom. The spacing ratio ranges from 1.0 to 5.0. The oncoming fluid velocity is U = 1–10 m/s, corresponding to the reduced velocity Ur = 3.81–38.08 and the Reynolds number Re = 9.58 × 103–9.58 × 104. Four harnessing damping ratios (ζharness = 0.0054–0.0216) are used to simulate the energy conversion conditions. The main conclusions are: (1) The optimal oscillation pattern related to the highest harnessed energy emerges as the spacing ratio close to 1.0. (2) The airflow energy converted by the foil is positively correlated with the harnessing damping ratio because the amplitude responses are similar at various harnessing damping ratios. A high velocity yields the highest harnessed power. (3) The harnessing efficiency of the foil could reach 48.89%, which is much more than that of an isolated flapping foil.

Aerodynamic evaluation of surgical design for the stenosis correction of airway.

Congenital tracheal stenosis (CTS) is a rare but life-threatening disease that can lead to respiratory dysfunction in children. Obstructive sleep apnea syndrome (OSAS) in children is characterized by prolonged partial upper airway obstruction and/or intermittent complete obstruction. Both of the diseases require surgical intervention. Although respective treatments of these two diseases are clear, there is a lack of literature discussing the surgical treatment of patients with CTS complicated by OSAS. We conducted a patient-specific study of patient with CTS complicated by OSAS. Computer-aided design was used to simulate surgical correction under different surgical sequences. Computational fluid dynamics was used to compare the outcomes of different sequences. Aerodynamic parameters, pressure drop, velocity streamlines, wall shear stress (WSS), and the ratio of airflow distribution and energy loss rate were evaluated. An obvious interaction was found between the two diseases in different surgical sequences. The order of correction for CTS or OSAS greatly affected the aerodynamic parameters and turbulence flows downstream of tracheal stenosis and upstream of epiglottis. The CTS and OSAS had mutual influences on each other on the aerodynamic parameters, such as pressure drops and WSS. When evaluating the priority of surgical urgency of CTS and OSAS, surgeons need to pay attention to the state of both CTS and OSAS and the physiological conditions of patients. The aerodynamic performance of the uneven airflow distribution and the potential impact caused by the correction of CTS should be considered in surgical planning and clinical management.

Simulation and experimental research on the optimization of airflow organization and energy saving in data centers using air deflectors

The airflow organization of the data center directly affects the temperature control performance and the energy efficiency of the cooling equipment. The servers at the bottom of the rack usually suffer from insufficient airflow rate and poor cooling effect. This is because of the limited distance between the bottom servers and the perforated floor, and the small horizontal velocity of the supply air flow. This study aims to improve the uniformity of the cooling airflow in the vertical direction of the rack by the air deflectors, thereby further improving the overall airflow organization in the data center. The size and installation of the deflectors in the data center were optimized according to both the experiment and numerical simulation results. From the results, it is recommended to install the deflector with a width of 100 mm at an angle of 45° under the perforated floor for the rack with the single-side airflow supply. For the rack with the double-side airflow supply, the width of the deflector should be 100 mm and installed at an angle of 30° to the perforated floor to achieve the best airflow distribution. Consequently, the intake airflow rate for the bottom servers significantly increased, and the occurrence of the local hot spots was effectively reduced. The numerical simulation of the airflow organization with and without the deflector was conducted by ANSYS. The results show that, the installation of the deflectors increased the inlet airflow rate for the rack by 16.98% and improved the energy efficiency of the dater center air conditioners by 1.98%.

Effects of structural parameters on air consumption and mechanical energy characteristics of airflow in the vortex spinning nozzle

Reducing energy consumption during textile production processes has currently become one of the key concerns. In order to design the nozzle of the vortex spinning machine with reduced air consumption, numerical simulation of the airflow in the nozzle is performed to investigate the effect of the length and the inlet diameter of the conical chamber in the intermediate section of the vortex tube on the air consumption and the mechanical energy characteristics of the airflow. A spinning experiment conducted to measure the flow rate and yarn tenacity is adopted to verify the numerical simulation results. The simulation results show that the air consumption of the nozzle is insignificantly affected as the length increases from 7.3 mm to 7.7 mm, while a decreasing trend has been found as the length increases from 7.7 mm to 8.1 mm. As the inlet diameter increases from 4.6 mm to 5.0 mm, the air consumption of the nozzle increases monotonically. The mechanical energy of airflow in the nozzle exhibits a minor difference between cases of lengths of 7.3 mm, 7.5 mm, and 7.7 mm, while it decreases significantly in cases of lengths of 7.9 mm and 8.1 mm. The mechanical energy of airflow in the vortex chamber increases as the inlet diameter increases. The experimental results are consistent with the numerical predictions. This work is expected to provide a reference for the design of the vortex spinning nozzle and an approach to reducing the energy consumption in the yarn production process.

A novel air balancing method based on an improved perceptron under multiple constraints for the energy conservation of ventilation system

Air balancing is a key technology for improving indoor environmental quality and reducing ventilation system energy consumption. Existing air balancing methods just considered damper angles and fan control voltages, combined as single constraint strategy to balance air. Fan power, as the direct parameter affecting system electricity consumption, has not been included in air balancing modelling. On the other hand, single constraint strategy makes current methods inflexible to maintain airflow accuracy and energy efficiency together. This paper proposes a novel air balancing energy-saving model with multiple constraint control strategy. Damper angle, fan control voltage, and fan power are combined by an improved perceptron model. It is aimed at minimizing ventilation system energy consumption, by achieving optimal airflow accuracy and energy conservation. The proposed improved perceptron under multiple constraints (IPMC) method is validated on the experimental system with 5 terminals, air balancing relative errors within 6.0 %. Compared with the current high-precision and energy-saving methods in references, IPMC reduces energy consumption by 12.0 % and 7.6 %, respectively, with improved airflow prediction accuracy. The proposed air balancing method has three innovation: 1) Constrained by the fan power, the IPMC method improves ventilation energy efficiency; 2) Independent and flexible constraints enable more accurate airflow control; 3) Integrated by an improved perceptron, multiple constraints consider airflow prediction accuracy and energy conservation at the same time. This method is expected to better satisfy airflow demand and reduce effectively energy consumption of ventilation system, thus improving building ventilation energy utilization efficiency without losing thermal comfort and indoor air quality.

Study on Airflow Distribution and Energy Conservation in a BSL-4 Laboratory Involved in Aerosol Infection Risk

In recent years, COVID-19 has occurred frequently in the world. The biosafety level 4 (BSL-4) laboratory personnel are at risk of being infected by bioaerosols. The high demand for fresh air makes the energy consumption of the laboratory far greater than that of ordinary buildings. This study aimed to propose a suitable air distribution design and reduce the energy consumption of the BSL-4 laboratory, which is beneficial for creating a healthy and green built environment. Firstly, the diffusion characteristics of aerosols, infection risk under different air distributions, and ventilation parameters were analyzed in depth. Secondly, from the perspective of negative pressure control, the influence of parameters such as air tightness and air changes on the airflow in multizone was discussed. The results indicated that the aerosol concentration under the same conditions of the upper supply-upper exhaust is 1.4 times higher than that of the upper supply-bottom exhaust after the airflow stabilizes. The impact of eddy currents on pollutant diffusion is weakened when the air supply velocity reduced from 1m/s to 0.8m/s. Finally, the energy-saving operation strategy was proposed with the optimized ventilation parameters. The results showed that this operation scheme reduced the energy consumption of the laboratory by 15-30%.

Vibration-coupled TENGs from weak to ultra-strong induced by vortex for harvesting low-grade airflow energy

Multi-direction, irregularity, low-grade, the dynamic characteristics of low-grade airflow energy are prominent that making it difficult to collect. Here, we propose a vibration-coupled triboelectric nanogenerator (VC-TENG) induced by vortex to achieve from weak to ultra-strong vibration, thus effectively converting low-grade airflow energy into vibrational mechanical energy, and then electric energy. The transferred charge and short-circuit current increases is 47 and 26.9 times due to designed vortex structure, and the resonant response time is 2 s at a speed of 4.1 m/s. A VC-TENG unit delivers a peak power of 4.5 mW under a load resistance of 500 MΩ. A grouping of applied demonstrations of self-powered system validates the practicality and durability of VC-TENG. This work offers a practical strategy for harvesting low-grade airflow energy, and is a promising distributed power technologies for self-powered monitoring and forecasting system in the wild.

Comparative study on the thermal characteristics under different air distribution strategies oriented to non-uniform environment: An indoor experiment

With the epidemic becoming normal and realizing carbon neutrality goals, many scholars are focusing on finding reasonable air distribution strategies to provide a healthy indoor environment effectively. Hence, this study conducted a comparative experiment on the thermal characteristics under different air distribution strategies, namely interactive cascade ventilation (ICV), displacement ventilation (DV), stratum ventilation (SV), and underfloor air distribution (UFAD). Visualized and objective experiments were introduced to investigate the airflow characteristic, energy consumption and thermal comfort. The research results demonstrate that while maintaining the same supply air volume, ICV has the fastest response rate with the shortest spread-over time. Due to the dependence on the thermal buoyancy of DV, its delivery time is up to 134s. With the visualization experiment going on for 60 s, the effective outdoor air of ICV is 25.6% and 26.6% higher than SV and UFAD, respectively. In terms of energy consumption, compared to SV and UFAD, ICV enhances temperature drop per unit cooling capacity (TDCC) by 28.5% and 36.8%, showing the most significant local control ability, which is of great significance for epidemic prevention and control as well. Although the local coefficient of cooling capacity utilization (LCU) under ICV is similar to that under DV, the ICV can reduce the sizeable vertical temperature gradients under DV and improve the temperature uniformity of the occupied zone by 77.5%. The conclusions obtained from this study can efficiently provide new insights for building a healthy indoor environment with the epidemic normalizing.

Combined Effects of Exterior Shading and A/C Heat Rejection on Building Energy Consumption and Indoor Air Pollution Exposure

Exterior shading devices and outdoor units can be closely coupled since these two building components are commonly installed next to each other. This study uses a coupled EnergyPlus-Fluent modeling approach to examine how a combination of exterior shading and heat rejection from outdoor units can affect the ambient outdoor environment of a building, and how changes in the ambient outdoor environment can influence cooling loads and indoor PM2.5 exposure. Three exterior shading devices were simulated, including horizontal overhangs, vertical overhangs, and vertical fins. Data from wind-tunnel experiments and field measurements were used to ensure the accuracy of the airflow model, energy model, and pollution model developed in this study. Results indicate that horizontal overhangs could almost offset the increase in cooling loads due to increased ambient outdoor temperatures caused by heat rejection. The use of vertical overhangs did not always mean lower demand for space cooling when heat rejection was considered. Heat rejection, horizontal overhangs, and vertical overhangs could help reduce indoor PM2.5 exposure, while indoor air pollution was worse after the implementation of vertical fins. This study shows how exterior shading devices and outdoor units can be coupled to achieve better building energy efficiency and improved occupant health.

A wind-solar energy harvester based on airflow enhancement mechanism for rail-side devices

A significant challenge arising from the rugged climate and environment is the provision of power to isolated railway-side equipment on the Plateau. Emerging renewable energy harvesting technologies present a promising solution. This paper proposes and confirms a Wind-Solar Energy Harvester (WSEH) founded on an Airflow Enhancement Mechanism (AFEM) for powering rail-side equipment. The proposed WSEH comprises of Vertical Axis Wind Turbine (VAWT), Flexible Photovoltaic Deflectors (FPVDs), and energy conversion and storage devices. The AFEM is executed founded on the FPVD that amplifies the airflow energy blown towards the VAWT due to the Blockage effect. The FPVD, grounded on an umbrella-like mechanism, unfolds as a PV panel for solar energy collection; and folds as a deflector to raise the wind energy collection potential for the VAWT. Through CFD simulation, the VAWT’s maximum power coefficient attains 0.387, and the optimum gain effect of FPVD is 66.54%. The prototypes, comprising VAWT and FPVDs, are scrutinized in a wind tunnel to authenticate the practicable effects illustrated by the no-load speed and load output of VAWT. The case study demonstrates that the WSEH creates 1566.82 kWh of electrical energy per year, sufficient for powering rail-side equipment on the Plateau.

Self-Powered Airflow Sensor Based on Energy Harvesting of Ventilation Air in Buildings

Heating, ventilation, and air conditioning (HVAC) systems account for one-third of the total energy consumption in office buildings. The use of airflow measurements to control the operation of HVAC systems can reduce energy consumption; thus, a sensor capable of monitoring airflow in a duct system is critical. Triboelectric nanogenerators (TENGs) can be utilized as self-powered sensors in airflow-driven TENGs (ATENGs) as self-powered sensors. By employing ferroelectric materials and surface modifications, the surface charges of TENGs can be increased. In this study, fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly (vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) and polyamide 11 (nylon-11). And these materials were subsequently investigated. Poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) was added to PVDF-TrFE to enhance the ferroelectric crystalline phase. X-ray diffraction analysis revealed that this incorporation affects the β phase. In addition, the surface of nylon-11 was modified using the electrospray technique for post-treatment, thereby improving the interfacial adhesion between the fibers. These materials were then utilized in fibrous-mat ATENGs (FM-ATENGs) to demonstrate their practical application. The FM-ATENGs can be effectively used in an Arduino airflow-check sensor, showcasing their potential for application in HVAC systems, to enhance airflow control and energy efficiency.Graphical

Improvement of the Airflow Energy Harvester Based on the New Diamagnetic Levitation Structure.

This paper presents an improved solution for the airflow energy harvester based on the push-pull diamagnetic levitation structure. A four-notch rotor is adopted to eliminate the offset of the floating rotor and substantially increase the energy conversion rate. The new rotor is a centrally symmetrical-shaped magnet, which ensures that it is not subjected to cyclically varying unbalanced radial forces, thus avoiding the rotor's offset. Considering the output voltage and power of several types of rotors, the four-notch rotor was found to be optimal. Furthermore, with the four-notch rotor, the overall average increase in axial magnetic spring stiffness is 9.666% and the average increase in maximum monostable levitation space is 1.67%, but the horizontal recovery force is reduced by 3.97%. The experimental results show that at an airflow rate of 3000 sccm, the peak voltage and rotation speed of the four-notch rotor are 2.709 V and 21,367 rpm, respectively, which are 40.80% and 5.99% higher compared to the three-notch rotor. The experimental results were consistent with the analytical simulation. Based on the improvement, the energy conversion factor of the airflow energy harvester increased to 0.127 mV/rpm, the output power increased to 138.47 mW and the energy conversion rate increased to 58.14%, while the trend of the levitation characteristics also matched the simulation results. In summary, the solution proposed in this paper significantly improves the performance of the airflow energy harvester.