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The Influence of the Diameter Ratio on the Characteristics Diagram of the Axial Compressor

Description: With the further development of axial blowers into highly loaded flow machines, the influence of the diameter ratio upon air output and efficiency gains in significance. Clarification of this matter is important for single-stage axial compressors, and is of still greater importance for multistage ones, and particularly for aircraft power plants. Tests with a single-stage axial blower gave a decrease in the attainable maximum pressure coefficient and optimum efficiency as the diameter ratio increased. The decrease must be ascribed chiefly to the guide surface of the hub and housing between the blades increasing with the diameter ratio.
Date: April 1948
Creator: Eckert, B.; Pflüger, F. & Weinig, F.
Partner: UNT Libraries Government Documents Department

Recent Results on High-Pressure Axial Blowers

Description: "Considerable progress has, in recent times, been attained in the development of the high-pressure axial blower by well-planned research. The efforts are directed toward improving the efficiencies, which are already high for the axial blower, and in particular the delivery pressure heads. For high pressures multistage arrangements are used. Of fundamental importance is the careful design of all structural parts of the blower that are subject to the effects of the flow. In the present report, several recent results and experiences are reported, which are based on results of German engine research" (p. 1).
Date: April 1947
Creator: Eckert, B.
Partner: UNT Libraries Government Documents Department

Possibilities of Reducing the Length of Axial Superchargers for Aircraft Motors

Description: Axial blowers are gaining importance as aircraft engine superchargers. However, the pressure head obtainable per stage is small. Due to the necessary great number of stages, the physical length of the blower becomes too great for an airworthy device. This report discusses several types of construction that permit a reduction in the length of the blower.
Date: January 1947
Creator: Eckert, B.
Partner: UNT Libraries Government Documents Department

Investigations on Experimental Impellers for Axial Blowers

Description: "A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented" (p. 1).
Date: April 1947
Creator: Encke, W.
Partner: UNT Libraries Government Documents Department

Constant-Pressure Blowers

Description: "The conventional axial blowers operate on the high-pressure principle. One drawback of this type of blower is the relatively low pressure head, which one attempts to overcome with axial blowers producing very high pressure at a given circumferential speed. The Schicht constant-pressure blower affords pressure ratios considerably higher than those of axial blowers of conventional design with approximately the same efficiency" (p. 1).
Date: January 1940
Creator: Sörensen, E.
Partner: UNT Libraries Government Documents Department

Tests of Propeller-Speed Cooling Blowers

Description: Report presenting testing of cooling blowers for air-cooled engine installations and an exploration of the methods used in the blower design and operating characteristics of the blowers over a range of flight speeds and altitudes. The results indicate that the blowers operate as a more efficient type of propeller cuff and in many cases provide considerably more pressure boost than using a cuff.
Date: July 1942
Creator: Silverstein, Abe
Partner: UNT Libraries Government Documents Department

Demand Controlled Filtration in an Industrial Cleanroom

Description: In an industrial cleanroom, significant energy savings were realized by implementing two types of demand controlled filtration (DCF) strategies, one based on particle counts and one on occupancy. With each strategy the speed of the recirculation fan filter units was reduced to save energy. When the control was based on particle counts, the energy use was 60% of the baseline configuration of continuous fan operation. With simple occupancy sensors, the energy usage was 63% of the baseline configuration. During the testing of DCF, no complaints were registered by the operator of the cleanroom concerning processes and products being affected by the DCF implementation.
Date: September 1, 2007
Creator: Faulkner, David; DiBartolomeo, Dennis & Wang, Duo
Partner: UNT Libraries Government Documents Department

New Methods of Energy Efficient Radon Mitigation

Description: Two new radon mitigation techniques are introduced and their evaluation in a field study complemented by numerical model predictions is described. Based on numerical predictions, installation of a sub gravel membrane at the study site resulted in a factor of two reduction in indoor radon concentrations. Experimental data indicated that installation of 'short-circuit' pipes extending between the subslab gravel and outdoors, caused an additional factor of two decrease in the radon concentration. Consequently, the combination of these two passive radon mitigation features, called the membrane and short-circuit (MASC) technique, was associated with a factor of four reduction in indoor radon concentration. The energy-efficient active radon mitigation method, called efficient active subslab pressurization (EASP), required only 20% of the fan energy of conventional active subslab depressurization and reduced the indoor radon concentration by approximately a factor of 15, including the numerically-predicted impact of the sub-gravel membrane.
Date: May 1, 1994
Creator: Fisk, W.J.; Prill, R.J.; Wooley, J.; Bonnefous, Y.C.; Gadgil, A.J. & Riley, W.J.
Partner: UNT Libraries Government Documents Department

Standard Methods of Characterizing Performance of Fan FilterUnits, Version 3.0

Description: We describe a fast contour descriptor algorithm and its application to a distributed supernova detection system (the Nearby Supernova Factory) that processes 600,000 candidate objects in 80 GB of image data per night. Our shape detection algorithm reduced the number of false positives generated by the supernova search pipeline by 41% while producing no measurable impact on running time. Fourier descriptors are an established method of numerically describing the shapes of object contours, but transform-based techniques are ordinarily avoided in this type of application due to their computational cost. We devised a fast contour descriptor implementation for supernova candidates that meets the tight processing budget of the application. Using the lowest-order descriptors (F{sub 1} and F{sub -1}) and the total variance in the contour, we obtain one feature representing the eccentricity of the object and another denoting its irregularity. Because the number of Fourier terms to be calculated is fixed and small, the algorithm runs in linear time, rather than the O(n log n) time of an FFT. Constraints on object size allow further optimizations so that the total cost of producing the required contour descriptors is about 4n addition/subtraction operations, where n is the length of the contour.
Date: January 1, 2007
Creator: Xu, Tengfang
Partner: UNT Libraries Government Documents Department

Advanced Energy-Efficient Filtration: Fan Filter Unit

Description: The objective of this project is to provide assistance in development of a standard test procedure for fan-filter units, which are gaining popularity for use in California cleanrooms. In particular, LBNL carried out collaboration with various stakeholders in the industry and took a lead in developing a draft standard method for testing the energy performance of fan-filter units, and provided assistance to California public utility companies by testing the draft method in PG&E's testing facility. Through testing more units in the future with a robust standard method, baseline performance information can be developed for use in possible energy incentive programs.
Date: October 1, 2005
Creator: Xu, Tengfang
Partner: UNT Libraries Government Documents Department

An Innovative Method for Dynamic Characterization of Fan FilterUnit Operation.

Description: Fan filter units (FFU) are widely used to deliver re-circulated air while providing filtration control of particle concentration in controlled environments such as cleanrooms, minienvironments, and operating rooms in hospitals. The objective of this paper is to document an innovative method for characterizing operation and control of an individual fan filter unit within its operable conditions. Built upon the draft laboratory method previously published [1] , this paper presents an updated method including a testing procedure to characterize dynamic operation of fan filter units, i.e., steady-state operation conditions determined by varied control schemes, airflow rates, and pressure differential across the units. The parameters for dynamic characterization include total electric power demand, total pressure efficiency, airflow rate, pressure differential across fan filter units, and airflow uniformity.
Date: December 21, 2006
Creator: Xu, Tengfang
Partner: UNT Libraries Government Documents Department

Long-term slip rate of the southern San Andreas Fault, from 10Be-26Al surface exposure dating of an offset alluvial fan

Description: We determine the long-term slip rate of the southern San Andreas Fault in the southeastern Indio Hills using {sup 10}Be and {sup 26}Al isotopes to date an offset alluvial fan surface. Field mapping complemented with topographic data, air photos and satellite images allow to precisely determine piercing points across the fault zone that are used to measure an offset of 565 {+-} 80 m. A total of twenty-six quartz-rich cobbles from three different fan surfaces were collected and dated. The tight cluster of nuclide concentrations from 19 samples out of 20 from the offset fan surface implies a simple exposure history, negligible prior exposure and erosion, and yield an age of 35.5 {+-} 2.5 ka. The long-term slip rate of the San Andreas Fault south of Biskra Palms is thus 15.9 {+-} 3.4 mm/yr. This rate is about 10 mm/yr slower than geological (0-14 ka) and short-term geodetic estimates for this part of the San Andreas Fault implying changes in slip rate or in faulting behavior. This result puts new constraints on the slip rate of the San Jacinto and on the Eastern California Shear Zone for the last 35 ka. Our study shows that more sites along the major faults of southern California need to be targeted to better constrain the slip-rates over different time scales.
Date: January 13, 2006
Creator: der Woerd, J v; Klinger, Y; Sieh, K; Tapponnier, P; Ryerson, F & M?riaux, A
Partner: UNT Libraries Government Documents Department

Control of Computer Room Air Conditioning using IT Equipment Sensors

Description: The goal of this demonstration was to show how sensors in IT equipment could be accessed and used to directly control computer room air conditioning. The data provided from the sensors is available on the IT network and the challenge for this project was to connect this information to the computer room air handler's control system. A control strategy was developed to enable separate control of the chilled water flow and the fans in the computer room air handlers. By using these existing sensors in the IT equipment, an additional control system is eliminated (or could be redundant) and optimal cooling can be provided saving significant energy. Using onboard server temperature sensors will yield significant energy reductions in data centers. Intel hosted the demonstration in its Santa Clara, CA data center. Intel collaborated with IBM, HP, Emerson, Wunderlich-Malec Engineers, FieldServer Technologies, and LBNL to install the necessary components and develop the new control scheme. LBNL also validated the results of the demonstration.
Date: September 30, 2009
Creator: Bell, Geoffrey C.; Storey, Bill & Patterson, Michael K.
Partner: UNT Libraries Government Documents Department

A Tip Driven Fan Based on SERAPHIM Technology

Description: SERAPHIM technology appears capable of efficiently driving a tip driven fan. If the motor is powered using an inverter and resonant circuit, the size and weight could be considerably below that of a comparable rotary electric motor.
Date: January 1, 2002
Partner: UNT Libraries Government Documents Department

Indoor Pollutant Mixing Time in an Isothermal Closed Room: An Investigation Using CFD

Description: We report on computational fluid dynamics (CFD) predictions of mixing time of a pollutant in an unventilated, mechanically mixed, isothermal room. The study aims to determine: (1) the adequacy of the standard Reynolds Averaged Navier Stokes two-equation ({kappa}-{var_epsilon}) turbulence model for predicting the mixing time under these conditions and (2) the extent to which the mixing time depends on the room airflow, rather than the source location within the room. The CFD simulations modeled the 12 mixing time experiments performed by Drescher et al. (Indoor Air 5 (1995) 204) using a point pulse release in an isothermal, sealed room mechanically mixed with variable power blowers. Predictions of mixing time were found in good agreement with experimental measurements, over an order of magnitude variation in blower power. Additional CFD simulations were performed to investigate the relation between pollutant mixing time and source location. Seventeen source locations and five blower configurations were investigated. Results clearly show large dependence of the mixing time on the room airflow, with some dependence on source location. We further explore dependence of mixing time on the velocity and turbulence intensity at the source location. Implications for positioning air-toxic sensors in rooms are briefly discussed.
Date: July 1, 2003
Creator: Gadgil, A. J.; Lobscheid, C.; Abadie, M. O. & Finlayson, E. U.
Partner: UNT Libraries Government Documents Department

Best Practice for Energy Efficient Cleanrooms: Fan-FilterUnits

Description: The HVAC systems in cleanrooms may use 50 percent or more of the total cleanroom energy use. Fan energy use accounts for a significant portion (e.g., over 50%) of the HVAC energy use in cleanrooms such as ISO Classes 3, 4, or 5. Three types of air-handling systems for recirculating airflows are commonly used in cleanrooms: (1) fan-tower systems with pressurized plenum, (2) ducted HEPA systems with distributed-fans, and (3) systems with fan-filter units. Because energy efficiency of the recirculation systems could vary significantly from system type to system type, optimizing aerodynamic performance in air recirculation systems appears to be a useful approach to improve energy efficiency in cleanrooms. Providing optimal airflows through careful planning, design and operation, including air change rate, airflow uniformity, and airflow speed, is important for controlling particle contamination in cleanrooms. In practice, the use of fan-filter units (FFUs) in the air-handling system is becoming more and more popular because of this type of system may offer a number of advantages. Often modular and portable than traditional recirculation airflow systems, FFUs are easier to install, and can be easily controlled and monitored to maintain filtration performance. Energy efficiency of air handling systems using fan-filter units can, however, be lower than their counterparts and may vary significantly from system to system because of the difference in energy performance, airflow paths, and the operating conditions of FFUs.
Date: June 15, 2005
Creator: Xu, Tengfang
Partner: UNT Libraries Government Documents Department

Best Practice for Energy Efficient Cleanrooms:Minienvironments

Description: Cleanroom air-recirculation systems typically account for a significant portion of the HVAC energy use in cleanrooms. High electric power density is normally required for fans to deliver large volume of airflows that were designed, supplied, recirculated, and exhausted within a given time. With the increasing demand for specific contamination control, it is important to optimize design of clean spaces. Best practice in cleanroom air system design includes right-sizing the systems in cleanrooms and adopting minienvironments. Implementing and integrating minienvironments in cleanrooms can improve contamination control and save significant energy. A minienvironment is a localized environment created by an enclosure to isolate a product or process from the surrounding environment. The advantages in using minienvironments include the following: (1) Minienvironments may create better contamination control and process integration. (2) Minienvironments may maintain better contamination control by better control of pressure difference or through use of unidirectional airflows, e.g., cleanliness-class upgrade required for certain process. (3) Minienvironments may potentially reduce energy costs. The use of fan-filter units (FFU) in minienvironments is common. The energy efficiency of such air-delivery systems can vary significantly because of the difference in energy performance, airflow paths, and operating conditions. Simply adding minienvironments with fan-filter units in an existing cleanroom will increase power density and energy intensity for delivering airflow in the space served, if everything else is unchanged. However, by considering contamination control requirements in the various spaces minienvironments can be integrated with the surrounding cleanroom to optimize the overall electric power demand for the facility and to achieve specific cleanliness in each area. In addition, selecting energy efficient minienvironment systems will further improve the overall energy efficiency of the clean spaces.
Date: June 15, 2005
Creator: Xu, Tengfang
Partner: UNT Libraries Government Documents Department

Effects of room furnishings and air speed on particle depositionrates indoors

Description: Particle deposition to surfaces plays an important role in determining exposures to indoor particles. However, the effects of furnishings and air speed on these rates have not been well characterized. In this study, experiments were performed in an isolated room (volume = 14.2 m{sup 3}) using three different indoor furnishing levels (bare, carpeted and fully furnished) and four different airflow conditions. Deposition loss rates were determined by generating a short burst of polydispersed particles, then measuring the size-resolved (0.5-10 {micro}m) concentration decay rate using an aerodynamic particle sizer. Increasing the surface area from bare (35 m{sup 2} nominal surface area) to fully furnished (12 m{sup 2} additional surface area) increased the deposition loss rate by as much as a factor of 2.6, with the largest increase seen for the smallest particles. Increasing the mean airspeed from < 5 cms/s to 19 cm/s, by means of increasing fan speed, increased the deposition rate for all particle sizes studied by factors ranging from 1.3 to 2.4, with larger particles exhibiting greater effects than smaller particles. The significant effect of particle size and room conditions on deposition loss rates argues against using a single first-order loss-rate coefficient to represent deposition for integrated mass measurements (PM{sub 2.5} or PM{sub 10}).
Date: June 1, 2002
Creator: Thatcher, Tracy L.; Lai, Alvin C.K.; Moreno-Jackson, Rosa; Sextro, Richard G. & Nazaroff, William W.
Partner: UNT Libraries Government Documents Department

LAB 3 Cleanroom Fan and Filters Analysis for the Supports

Description: A 1400 lb blower fan and a 2700 lb filter box are to be supported at Lab 3. The support structure is a framework that suspends from the building wall to the cleanroom and to a washroom. The framework is made of welded 4-inch x 8-inch x 1/4-inch rectangular A36 steel tube. Welds are to be standard prequalified welds as by AISC. The main support frame is approximately 7-feet off the floor and welded onto the top of 10 columns. A deflection and stress study was performed on the planned structure. A scaled plan view is given in drawing 3823.113-MD-358764. The heaviest loaded beams were labeled with a letter designation and were studied for beam deflections and stresses. The 4-inch x 8-inch rectangular tube was also used for the substructure for the fan and filter mounts and to support a temporary floor grating during maintenance.
Date: May 8, 1998
Creator: Cease, H.
Partner: UNT Libraries Government Documents Department

Review of Literature on Terminal Box Control, Occupancy Sensing Technology and Multi-zone Demand Control Ventilation (DCV)

Description: This report presents an overall review of the standard requirement, the terminal box control, occupancy sensing technology and DCV. There is system-specific guidance for single-zone systems, but DCV application guidance for multi-zone variable air volume (VAV) systems is not available. No real-world implementation case studies have been found using the CO2-based DCV. The review results also show that the constant minimum air flow set point causes excessive fan power consumption and potential simultaneous heating and cooling. Occupancy-based control (OBC) is needed for the terminal box in order to achieve deep energy savings. Key to OBC is a technology for sensing the actual occupancy of the zone served in real time. Several technologies show promise, but none currently fully meets the need with adequate accuracy and sufficiently low cost.
Date: March 1, 2012
Creator: Liu, Guopeng; Dasu, Aravind R. & Zhang, Jian
Partner: UNT Libraries Government Documents Department

Modelica-based Modeling and Simulation to Support Research and Development in Building Energy and Control Systems

Description: Traditional building simulation programs possess attributes that make them difficult to use for the design and analysis of building energy and control systems and for the support of model-based research and development of systems that may not already be implemented in these programs. This article presents characteristic features of such applications, and it shows how equation-based object-oriented modelling can meet requirements that arise in such applications. Next, the implementation of an open-source component model library for building energy systems is presented. The library has been developed using the equation-based object-oriented Modelica modelling language. Technical challenges of modelling and simulating such systems are discussed. Research needs are presented to make this technology accessible to user groups that have more stringent requirements with respect to the numerical robustness of simulation than a research community may have. Two examples are presented in which models from the here described library were used. The first example describes the design of a controller for a nonlinear model of a heating coil using model reduction and frequency domain analysis. The second example describes the tuning of control parameters for a static pressure reset controller of a variable air volume flow system. The tuning has been done by solving a non-convex optimization problem that minimizes fan energy subject to state constraints.
Date: February 12, 2009
Creator: Wetter, Michael
Partner: UNT Libraries Government Documents Department