Air Flow Meters Research Articles

Occupancy sensor-enabled demand control ventilation using virtual outdoor air flow meters in air handling units without an outdoor air flow meter

Nowadays, the outdoor air (OA) flow requirement for demand control ventilation (DCV) can be accurately determined using occupancy sensors in commercial buildings. However, in air handling units (AHUs) without precise OA flow measurements, the OA is often controlled by a fixed-damper position method, which cannot maintain the required OA flow rate. The objective of this study is to develop and evaluate occupancy sensor-enabled DCV OA control using a virtual OA flow meter in AHUs. Firstly, a virtual OA flow meter is derived from a virtual supply fan flow meter by applying the correlation between the OA ratio and damper position under appropriate building pressure control. Subsequently, experiments are conducted to calibrate the virtual OA flow meter in an AHU with the design OA flow rate of 120 L/s. Finally, occupancy sensor-enabled DCV OA control is implemented by using the calibrated virtual OA flow meter. The evaluation results show that the proposed DCV OA control can match the actual OA flow rate well with the required OA flow rate. The root mean squared error (RMSE) falls within the range of 16–20 L/s, demonstrating an improvement over the fixed-damper position control, which yields an RMSE of 36 L/s.

Intelligent Combustion Control of the Hot Blast Stove: A Reinforcement Learning Approach

Combustion optimization of hot blast stoves is a promising approach for cost savings and energy conservation of ironmaking. Existing artificial intelligence methods for this optimization rely on air and gas flow meters, which can malfunction under harsh working conditions. To meet this challenge, we propose an intelligent combustion control system based on reinforcement learning (RL). Considering the difficulty of learning state feature representation, five RL models using different deep embedding networks were implemented and evaluated. The Attention-MLP-based RL model is distinguished through experimental testing, achieving an accuracy of 85.91% and an average inference time of 4.85 ms. Finally, the intelligent combustion control system with the Attention-MLP-based RL model runs in the hot blast stove of the blast furnace (1750 m3 in volume) at Tranvic Steel Co., Ltd. in China (Chengdu, China). The results show that our system can achieve good control performance by autonomously learning the implicit relationship between the state of the hot blast stove and the valve control action in the absence of flow meters.

Accuracy of a hand-held resistance-free flowmeters for flow adjustments of Hirst-Type pollen traps

The Hirst-type pollen trap (1952) is the most common device for aerobiological measurements of pollen and fungal spores in ambient air. In the 1960s the in-line flowmeter was removed and studies since then showed considerable variability in the airflow pumped through the instrument when using hand-held rotameters with an internal airflow resistance to adjust flowrates. To avoid this problem, our study compared the variability of airflow rates of Hirst-type traps when using commercially-available low-resistance airflow meters (heat anemometers) at various timescales. Experiments were conducted in Munich (Germany) and Payerne (Switzerland), using 4 different easyFlux® instruments and 6 Hirst-type pollen traps. Measurements were taken on an hourly basis from dawn to dusk at both locations, and in addition at Payerne, weekly observations over a period of one year. When using the common hand-held rotameters (with airflow resistance) the flow was 28.3% lower than with resistance-free flowmeter (i.e., measured 10 L/min which was in reality 12.8 L/min). The coefficient of variation between the four easyFlux® devices ranged from 0.32% to 1.55% over one day and from 2.88% to 8.17% over an entire year. Some of the traps showed surprising flow variations during the day. Furthermore, flowrates deviated more when measurements were made at the point where the double-sided tape is behind the orifice than elsewhere on the drum. The measurements away from this point are representative of the flow rates for most of the period of operation and flow calibration should thus be carried out away from this point, contrary to the current procedure.

ELMO, a new helmet interface for CPAP to treat COVID-19-related acute hypoxemic respiratory failure outside the ICU: a feasibility study.

ABSTRACTObjective:To assess the feasibility of using a new helmet interface for CPAP, designated ELMO, to treat COVID-19-related acute hypoxemic respiratory failure (AHRF) outside the ICU. Methods:This was a proof-of-concept study involving patients with moderate to severe AHRF secondary to COVID-19 admitted to the general ward of a public hospital. The intervention consisted of applying CPAP via the ELMO interface integrated with oxygen and compressed air flow meters (30 L/min each) and a PEEP valve (CPAP levels = 8-10 cmH2O), forming the ELMOcpap system. The patients were monitored for cardiorespiratory parameters, adverse events, and comfort. Results:Ten patients completed the study protocol. The ELMOcpap system was well tolerated, with no relevant adverse effects. Its use was feasible outside the ICU for a prolonged amount of time and was shown to be successful in 60% of the patients. A CPAP of 10 cmH2O with a total gas flow of 56-60 L/min improved oxygenation after 30-to 60-min ELMOcpap sessions, allowing a significant decrease in estimated FIO2 (p = 0.014) and an increase in estimated PaO2/FIO2 ratio (p = 0.008) within the first hour without CO2 rebreathing. Conclusions:The use of ELMOcpap has proven to be feasible and effective in delivering high-flow CPAP to patients with COVID-19-related AHRF outside the ICU. There were no major adverse effects, and ELMO was considered comfortable. ELMOcpap sessions significantly improved oxygenation, reducing FIO2 without CO2 rebreathing. The overall success rate was 60% in this pilot study, and further clinical trials should be carried out in the future.(ClinicalTrials.gov identifier: NCT04470258 [http://www.clinicaltrials.gov/])

Construction and experimental research of multifunctional hybrid powertrain test bench

With the development of hybrid electric vehicles, the demand for test benches is becoming more and more vigorous. Based on the traditional engine test bench, this paper builds a multifunctional hybrid powertrain test bench by matching appropriate equipment such as battery simulators, power analyzers, fuel consumption meters, and air flow meters. The test bench has the characteristics of modularization, flexibility, and multi-function. It can be used for testing single engine, single generator and hybrid power system. Finally, the range extender produced by a domestic manufacturer was used as the test object, and the endurance test was carried out on the modified test bench. The test further verified the reliability and feasibility of the multifunctional hybrid powertrain test bench.

Numerical Study of Single-Hole and Multi-Holes Orifice Flow Parameters

Importance of accurate fluid flow measurement in industry is crucial especially today with rising energy prices. There is no ideal measuring instrument due to numerous errors occurring during process of physical quantities measurement but also due to specific requirements certain instruments have like fluid type, installation requirements, measuring range etc. Each measuring instrument has its pros and cons represented in accuracy, repeatability, resolution, etc. Conventional single-hole orifice (SHO) flow meter is a very popular differential-pressure-based measuring instrument, but it has certain disadvantages that can be overcame by multi-holes orifice (MHO) flow meter. Having this in mind, the aim of this paper is to help gain more information about MHO flow meters. Both SHO and MHO gas (air) flow meters with same total orifice area and the pipe area ratio β were numerically studied and compared using computational fluid dynamics (CFD). Simulation results of 16 different orifices with four different β (0.5, 0.55, 0.6 and 0.7) were analysed through pressure drop and singular pressure loss coefficient. Standard k-ε turbulence model was used as a turbulence model. Beside singular pressure loss coefficient, pressure recovery as well as axial velocity for both the SHO and MHO were reported. Results showed lower (better) singular pressure loss coefficient and pressure drop as well as quicker pressure recovery in favour of the MHO flow meters. Also, centreline axial velocity results were lower for MHO compared to corresponding SHO. CFD simulation results were verified by experimental results where air was used as a working fluid. The influence of geometrical and flow parameters on singular pressure loss coefficient was also reported and results showed that MHO hole distribution did not have significant influence on singular pressure loss coefficient.

Development of a virtual fan airflow meter for electronically commutated motor fan systems

Airflow measurement is essential to efficiently operate air handling units (AHUs) in commercial buildings. Due to the space and cost limitations for physical meters, many virtual airflow meters have been developed for induction motor driven fan systems. On the other hand, electronically commutated motor (ECM) fans have been widely applied in AHUs. However, the applicability of virtual airflow meters to ECM fan systems remains unclear. The purpose of this paper is to develop and validate a virtual airflow meter for ECM fan systems using measured fan head and motor input power and speed. First, a virtual airflow meter model is developed by referring to an ECM fan energy model and the corresponding calibration procedure is established, then the developed model is calibrated using the manufacturer data of a 7,865 m3/h ECM fan, including fan airflow rate, head and motor input power at different motor speeds, and validated in a test AHU with an array of four calibrated ECM fans. The validation result shows that the developed meter can accurately calculate the total AHU airflow rate with the root mean squared error of 660 m3/h and the normalized root mean squared error of 4%.

Noise Level and Comfort in Healthy Subjects Undergoing High-Flow Helmet Continuous Positive Airway Pressure.

The aim of this study was to assess the noisiness levels produced by different gas source systems, breathing circuits setup, and gas flow rates during continuous positive airway pressure (CPAP) delivered through helmet. This was a crossover design study. Ten healthy subjects received helmet CPAP at 5 cm H2O in random order with different gas flow rates (60 and 80 L/min), 3 diverse gas source systems (A: Venturi system, B: oxygen and air flowmeters, C: electronic Venturi system), and 3 different breathing circuit configurations. During every step of this study, a heat and moisture exchanger (HME) was placed on the helmet inlet gas port to measure the effects on noise production. Noise intensity level was recorded through a sound-level meter. Participants scored their noisiness perception on a visual analog scale. The noise level inside the helmet ranged between 76 ± 4 and 117 ± 1 Decibel A. The gas source and the gas flow rate always affected the noise level inside and outside the helmet (P < .001). The different "breathing circuit setup" did not change the noise levels inside the helmet (P = .244), but affected the noise level outside, especially when a Venturi system was used (P < .001). An HME filter placed at the junction between the inspiratory limb of the breathing circuit and the helmet significantly decreased the noise intensity inside the helmet (mean dBA without HME, 99.56 ± 13.30 vs 92.26 ± 10.72 with HME; P < .001) and outside (mean dBA without HME, 68.16 ± 12.05 vs 64.97 ± 12.17 with HME; P < .001). The perception of noise inside the helmet was lower when an HME filter was placed on the inspiratory inlet gas port (median, 6 [interquartile range, 4-7] vs 7 [5-8]; P < .001). When helmet CPAP is delivered through gas flow rates up to 50 L/min, an HME placed on the helmet inlet gas port should be used to reduce noise inside the helmet and to improve patients' comfort.

Effect of the Air Flow Angle on a Microbubble Generator with a Spherical Body

This research has been carried out on the characteristics of a microbubble generator in a spherical body. It aims to study the influence of the air flow angle on generated bubble characteristics. A water loop system consisting of a water reservoir, an observation box, a pump, water and air flow meters, valves and a test section is used. The test section is a microbubble generator in the shape of a spherical body. Three types of microbubble generator with various air flow angles have been used as a test section at various water flowrates, air flowrates and height of water in reservoir. The tested parameter significantly influences the number and the size of the bubbles. Increasing the air flowrate increases the size of the bubbles, while increasing the water flowrate increases the number of microbubbles. The effect of the air flow angle in the microbubble generator is significant. A Microbubble generator with a 45° air flow angle produces a larger size of bubbles compared to a direct (0° air flow angle) microbubble generator. A microbubble generator with a 90° air flow angle could not suck up the air more than 0.1 lpm, so it is inefficient to produce bubble. From this study it is concluded that a microbubble generator is capable of producing microbubbles and the number and the size of bubbles is affected by the air flow angle.

HIGH-PRECISION ONBOARD FUEL LEVEL CONTROL AND MEASUREMENT SYSTEM

The fueling systems of modern aircraft are considered. The need for their further improvement is shown in accordance with the recommendations of ICAO. A brief overview of methods and means of measuring fuel level in tanks in modern aviation fuel meters are given. It is proposed to develop and create high-precision air flowmeters and to develop a structure based on the measurement of the cost of fuel oil in tanks with automatic stabilization of air pressure in the tank. The designs of the diaphragm knot and the differential pressure gauge included in the volumetric fueling system are considered. The developed system allows to create equipment with the improved characteristics.

Experimental study on interfacial area transport of two-phase bubbly flow in a vertical large-diameter square duct

In this paper, an experimental study on the atmospheric upward bubbly air–water flows in a vertical large-diameter square duct flow channel (cross-sectional sizes, 100 mm × 100 mm, hydraulic equivalent diameter, DH = 0.1 m and height, 3 m) have been performed by mainly using four-sensor probes. The four-sensor probes with the latest four-sensor probe method of Shen and Nakamura (2014) were applied in the local measurements at 3 axial positions (z/DH = 8.3, 18.3 and 28.3) to obtain interfacial area concentration (IAC), 3D bubble velocity vector and bubble diameter for the complex flow structure. The measurements were carried out locally at 66 points in an octant symmetric triangular zone in the cross-section at each axial position. The agreements between these local measurement results of the four-sensor probes and the measured results from the differential pressure gauges and the air flow meters are ± 7.97% in average relative measurement error for void fraction and ± 8.67% in average relative measurement error for superficial gas velocity. The obtained void fraction, IAC, 3D bubble velocity vector and bubble diameter serve as a valuable database relating to the cross-sectional local profiles and axial flow development and provide valuable insight into the local flow structure and behavior in the corresponding flow regimes. Although the interfacial area transport equation (IATE) and its bubble coalescence and breakup models have already played an important role in predicting the IAC in general two-phase flow fields now, they are mainly developed based on the two-phase flow experimental data taken in round pipes or small diameter channels with different shapes. To confirm their usability in the two-phase flow in large-diameter square duct, this study has evaluated the 1D one-group IATE with its 6 sets of bubble coalescence and breakup models with the presently-obtained database. The IATE with the bubble coalescence and breakup model of Sun et al. (2004a) has been concluded to give the best prediction for the IAC in the two-phase bubbly flow in the large-diameter square duct with a mean absolute relative error of 25.10%. It is highly desirable to develop a more accurate bubble coalescence and breakup model considering the complex turbulence in large-diameter square ducts.

Investigation of the sound generation mechanisms for in-duct orifice plates.

Sound generation due to an orifice plate in a hard-walled flow duct which is commonly used in air distribution systems (ADS) and flow meters is investigated. The aim is to provide an understanding of this noise generation mechanism based on measurements of the source pressure distribution over the orifice plate. A simple model based on Curle's acoustic analogy is described that relates the broadband in-duct sound field to the surface pressure cross spectrum on both sides of the orifice plate. This work describes careful measurements of the surface pressure cross spectrum over the orifice plate from which the surface pressure distribution and correlation length is deduced. This information is then used to predict the radiated in-duct sound field. Agreement within 3 dB between the predicted and directly measured sound fields is obtained, providing direct confirmation that the surface pressure fluctuations acting over the orifice plates are the main noise sources. Based on the developed model, the contributions to the sound field from different radial locations of the orifice plate are calculated. The surface pressure is shown to follow a U3.9 velocity scaling law and the area over which the surface sources are correlated follows a U1.8 velocity scaling law.

Gas-liquid bubbly flow structure in a vertical large-diameter square duct

An experimental study was performed on the local structure of atmospheric upward-moving air–water two-phase flow in a vertical large-diameter square duct with a cross-section of 100 mm × 100 mm and a height of 3 m by using a four-sensor probe at the axial position of z/DH = 29.2. The flow regime was simultaneously observed by a high speed camera at z/DH = 12.5. The four-sensor probe method classifying spherical and non-spherical bubbles was applied as a key measurement way to obtain local parameters such as 3-D bubble velocity vector, bubble diameter and interfacial area concentration, which are necessary for people to know the internal flow structures as well as local void fraction change. The local measurements were performed at 66 points within an octant symmetric triangular area of the cross-section, which agreed well with area-averaged void fractions from differential pressure gauges and the superficial gas velocity from air flow meters. Both the local void fraction and interfacial area concentration indicated radial core-peak and wall-peak distributions at low and high liquid flow rates respectively. Main flow component of the bubble velocity vector showed a power-law distribution shape with its center peak increasing with the liquid flow rate. The 2 components of the bubble velocity vector in the cross-section revealed that there exists a rotating secondary flow in the octant symmetric triangular area and the magnitude of the rotating secondary flow increases with the liquid flow rate. Some of constitutive correlations of drift-flux model for rectangular flow channels and large-diameter circular flow channels and interfacial area concentration correlations for small-diameter and large-diameter circular flow channels are selected and reviewed to study their predictabilities against the present experimental data. The comparison study shows that the drift-flux correlations by Hibiki and Ishii (2003) reasonably predict void fraction and the interfacial-area-concentration correlations by Hibiki and Ishii (2002) and Shen and Hibiki (2015) can be recommended for the prediction of interfacial area concentration in the bubbly flows in large-diameter square ducts.

Leak-Based Method for the Measurement of Air Permeability of Papers

Summary The air permeability of cigarette paper is currently assessed according to the international standard ISO 2965 by applying a constant pressure difference of 1 kPa between the two faces of a sample and by measuring the corresponding airflow. Lower Ignition Propensity regulations have led tobacco manufacturers to use specific cigarette papers with narrow bands of low air permeability and diffusion capacity to achieve regulatory compliance. The international standard ISO 2965 was revised in 2009 to take into account the specific geometry and characteristics of the bands and to include suitable narrow measuring heads. The consequence was a significant reduction of the measured airflow levels with banded papers and a need for equipment covering specifically low airflow ranges. The well-known pressure-airflow relationship across cigarette paper enables the development of an alternative method to ISO 2965 which does not require direct airflow measurement, and therefore airflow meters which are costly parts of the current measuring devices. The alternative method is based on the measurement of the change of the pressure over time after an initial pressure difference was applied between the two faces of the paper. The consecutive analysis of the pressure difference profile, impacted by the leak across the paper, enables the derivation of the air permeability. The related theoretical aspects were developed for both viscous and inertial airflows, and experimental investigations were conducted with banded and conventional cigarette papers as well as a permeability calibration standard. Results obtained with the proposed method showed good consistency with ISO 2965 measurements and a lower repeatability, demonstrating that a leak-based method could be a simple and reliable alternative.

Development of an ultrasonic airflow measurement device for ducted air.

In this study, an in-duct ultrasonic airflow measurement device has been designed, developed and tested. The airflow measurement results for a small range of airflow velocities and temperatures show that the accuracy was better than 3.5% root mean square (RMS) when it was tested within a round or square duct compared to the in-line Venturi tube airflow meter used for reference. This proof of concept device has provided evidence that with further development it could be a low-cost alternative to pressure differential devices such as the orifice plate airflow meter for monitoring energy efficiency performance and reliability of ventilation systems. The design uses a number of techniques and design choices to provide solutions to lower the implementation cost of the device compared to traditional airflow meters. The design choices that were found to work well are the single sided transducer arrangement for a “V” shaped reflective path and the use of square wave transmitter pulses ending with the necessary 180° phase changed pulse train to suppress transducer ringing. The device is also designed so that it does not have to rely on high-speed analogue to digital converters (ADC) and intensive digital signal processing, so could be implemented using voltage comparators and low-cost microcontrollers.

Concordance and Discriminatory Power of Cough Measurement Devices for Individuals With Parkinson Disease

Dysphagia and aspiration pneumonia are two causes of morbidity in Parkinson disease (PD). In PD, impaired airway clearance can lead to penetration of foreign material, resulting in a high prevalence of aspiration pneumonia and death. This study examines three different devices for measurement of peak airflow during voluntary cough in healthy control subjects and those with PD. Two simple and low-cost devices for measuring peak cough airflow were compared with the "gold standard" pneumotachograph. Thirty-five healthy control subjects and 35 individuals with PD produced voluntary cough at three perceived strengths (weak, moderate, and strong cough) for each of the three devices. A significant difference in mean peak cough airflow was demonstrated for disease (F[1,56] = 4.0, P &lt; .05) and sex (F[1,56] = 9.59, P &lt; .003) across devices. The digital and analog meters were comparable to the gold standard demonstrating no significant difference (statistical) by device (digital vs analog) in receiver operating characteristic curve analysis. Both devices were discriminative of the presence of PD. The analog and digital peak airflow meters are suitable alternatives to the gold standard pneumotachograph due to their low cost, portability, ease of use, and high sensitivity relative to normative peak cough airflows. Voluntary cough airflow measures may serve as a noninvasive means of screening for aspiration risk in target populations. Additionally, quantification of cough strength through use of predetermined limens for weak, moderate, and strong cough may assist clinicians in better describing and tracking cough strength as a contributing factor to aspiration risk.

Investigations on a virtual airflow meter using projected motor and fan efficiencies

Airflow measurements are not as accurate as needed in air-handling units due to space and cost limitations of physical meters. Generally, the airflow in an air-handling unit is propelled by a fan driven by a motor and, hence, the airflow rate is related to fan-motor system performance, which can be affected by other measurable variables, such as fan head and motor power. Theoretically, a virtual airflow meter can be developed to virtually obtain the airflow rate from measured fan head and motor power along with projected motor and fan efficiency models. Because variable frequency drives have been widely installed in HVAC systems, a comprehensive motor efficiency model is needed to project motor efficiency under variable frequency and voltage. At the same time, an in situ fan efficiency curve needs to be projected through a calibration process corresponding to actual fan head measurement. This article explores a theoretical model of virtual airflow meters in order to identify the relationship of fan airflow rate with measurable fan head, motor power, and power frequency and voltage; then, demonstrates a procedure to implement a virtual airflow meter and validate the virtual fan airflow meter through an experiment. The results show that airflow measurements from the virtual airflow meter match very well with a conventional duct mounted airflow meter with an standard deviation of 0.0177 m3/s (37.5 cubic feet per minute [CFM]) for instant measurement and 0.0142 m3/s (30.1 CFM) for a 5-min moving average with the measured airflow range between 0.45 m3/s (950 CFM) and 0.70 m3/s (1,480 CFM).

Stability and accuracy of variable air volume box control at low flows. Part 1: Laboratory test setup and variable air volume sensor test

Variable air volume systems with direct digital controllers have been widely adopted in the HVAC system of commercial, industrial, and large residential buildings because they provide better energy efficiency and occupant comfort. Normally, a variable air volume terminal unit defines a minimum airflow rate to satisfy the space ventilation requirement and/or the proper operation of a terminal heating coil, if so equipped. However, it has been found that variable air volume terminal units often fail to perform as expected at the minimum airflow range (below 500 fpm [2.5 m/s]). Under such a flow range, the embedded airflow sensor becomes inaccurate, and the designed minimum airflow rate is less than the minimum controllable airflow rate. This results in a series of problems, including lack of ventilation, uneven airflow control, reduced damper and operator life, and energy waste. Through designed laboratory and field tests, this study (ASRHAE Research Project RP-1353) aims to identify the major factors that cause inaccuracy and instability issues in variable air volume terminal units and the relationship between the major factors and performance of the airflow sensor, controller, and terminal unit system. Laboratory tests performed in this study included a variable air volume sensor test, controller test, and system test. Four variable air volume boxes from three manufacturers and four controllers from four manufacturers were tested systematically. Two identical test beds with high accuracy (±0.5%) reference airflow meters were designed and constructed in the test facility. The size of the reference airflow measuring stations was carefully selected to provide maximum airflow measuring accuracy and maximum available system pressure drop. This article describes the laboratory test setup and summarizes the variable air volume sensor test results. A companion article summarizes the controller test, system test, and field test results. From the variable air volume sensor test, three factors, namely, inlet conditions, low variable air volume damper positions, and low airflow rates, are identified as strongly impacting variable air volume terminal unit performance.

Development and In-situ validation of a multi-zone demand-controlled ventilation strategy using a limited number of sensors

This paper presents a new strategy using a limited number of sensors for demand-controlled ventilation (DCV) of multi-zone office buildings. The conventional CO2-based demand-controlled ventilation strategy for multi-zone offices requires CO2 sensors and supply airflow meters being installed in all zones. However, in many practical cases, CO2 sensors might not be available or not necessary. To control the outdoor airflow based on actual occupancy variations in such cases, a DCV strategy with two implementing schemes is developed for different sensor availabilities. The first scheme is used for the situation when CO2 sensors in individual zones are not available but the airflow meters for individual zones are installed. The second scheme is used for the conditions when CO2 sensors and airflow meters in individual zones are not available. These two schemes use two different approaches to estimate the outdoor airflow fraction of the critical zone approximately. Both schemes only require the CO2 sensor in the main return air to dynamically detect the total occupancy number. The developed strategy is implemented and validated in a high-rise office building in Hong Kong. The site test results show that the strategy can achieve significant energy saving while maintaining acceptable IAQ in the situations where only limited sensors are available.

Self-organizing sensing infrastructure for autonomic management of green datacenters

The scale and complexity of modern datacenters are growing at an alarming rate due to the rising popularity of the cloud computing paradigm as an effective means to cater to the ever increasing demand for computing and storage. The management of modern datacenters is rapidly exceeding human ability, making autonomic approaches essential. In this article, methods for acquiring thermal awareness using real-time measurements and heat and air circulation models as well as solutions for proactive autonomic datacenter management that exploit this awareness are discussed. Novel communication and coordination schemes that enable self-organization of a network of external heterogeneous sensors (e.g., thermal cameras, scalar temperature and humidity sensors, airflow meters) into a multitier sensing infrastructure capable of real-time datacenter monitoring are also presented.