320 research outputs found

    Laboratory Evaluation of Energy Recovery Ventilators

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    Preconditioning Outside Air: Cooling Loads from Building Ventilation

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    HVAC equipment manufacturers, specifiers and end users interacting in the marketplace today are only beginning to address the series of issues promulgated by the increased outside air requirements in ASHRAE Standard 62- 1989, "Ventilation for Acceptable Indoor Air Quality", that has cascaded into building codes over the early to mid 1990's. There has been a twofold to fourfold increase in outside air requirements for many commercial building applications, compared to the 1981 version of the standard. To mitigate or nullify these additional weather loads, outdoor air preconditioning technologies are being promoted in combination with conventional HVAC operations downstream as a means to deliver the required fresh air and control humidity indoors. Preconditioning is the term applied for taking outside air to the indoor air setpoint (dry bulb temperature and relative humidity). The large humidity loads from outside air can now be readily recognized and quantified at cooling design point conditions using the extreme humidity ratios/dew points presented in the ASHRAE Handbook of Fundamentals Chapter 26 "Climatic Design Information". This paper presents an annual index called the Ventilation Load Index (VLI), recently developed by the Gas Research Institute (GRI) that measures the magnitude of latent (and sensible) loads for preconditioning outside air to indoor space conditions over the come of an entire year. The VLI has units of ton-hrs/scfm of outside air. The loads are generated using new weather data binning software called ~BinMaker, also from GRI, that organizes the 239 city, 8760 hour by hour, TMY2 weather data into user selected bidtables. The VLI provides a simple methodology for accessing the cooling load impact of increased ventilation air volumes and a potential basis for defining a "humid" climate location

    Bubbly cavitating flow generation and investigation of its erosional nature for biomedical applications

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    This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.The paper presents a study of the generation of hydrodynamic bubbly cavitation in microchannels to investigate the destructive energy output resulting from this phenomenon and its potential use in biomedical applications. The research performed in this study includes the experimental results from bubbly cavitation experiments and the findings showing the destructive effects of bubbly cavitating flow on selected specimens and cells. The bubbles caused by hydrodynamic cavitation are highly destructive at the surfaces of the target medium on which they are carefully focused. The resulting destructive energy output could be effectively used for good means such as destroying kidney stones or killing infected cancer cells. Motivated by this potential, the cavitation damage (material removal) to cancerous cells and chalk pieces having similar material properties as calcium phosphate in human bones was investigated. Also the potential of hydrodynamic bubbly cavitation generated at the microscale for biomedical treatments was revealed using the microchannel configuration of a microorifice (with an inner diameter of 0.147 mm and a length of 1.52cm).This work was supported by Sabancı University Internal Grant for Research Program under Grant FRG-C47004

    Correlations Between Homeowner Mold Insurance Claims and Weather Databases in Texas

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    Experimental investigation of non-uniform heating effect on flow boiling instabilities in a microchannel-based heat sink

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    Copyright @ 2011 ElsevierTwo-phase flow boiling in microchannels is one of the most promising cooling technologies for coping with high heat fluxes produced by the next generation of central processor units (CPUs). If flow boiling is to be used as a thermal management method for high heat flux electronics it is necessary to understand the behaviour of a non-uniform heat distribution, which is typically the case observed in a real operating CPU. The work presented is an experimental study of two-phase boiling in a multi-channel silicon heat sink with non-uniform heating, using water as the cooling liquid. Thin nickel film sensors, integrated on the back side of the heat sinks were used in order to gain insight related to temperature fluctuations caused by two-phase flow instabilities under non-uniform heating. The effect of various hotspot locations on the temperature profile and pressure drop has been investigated. It was observed that boiling inside microchannels with axially non-uniform heating leads to high temperature non-uniformity in the transverse direction.This research was supported by the UK Engineering and Physical Sciences Research Council through grant EP/D500109/1

    Emerging, Cost-Effective Applications for Desiccant Dehumidification in the U.S.

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    Gas-fired desiccant dehumidification systems are now being specified for many supermarkets, ice arenas and cold warehouses, with installations now numbering in the thousands. Their cost effectiveness is due to the economic benefits of improved refrigeration operations resulting from the introduction of drier air. New application niches in the commercial sector are emerging due to the increased outside air quantities required by Indoor Air Quality codes and standards such as ASHRAE Standard 62- 1989. In this paper, a competitive economic analysis of desiccant and other HVAC equipment, generated using a new desiccant screening tool driven by DOE-2.1E simulations, will be presented for several representative buildings in selected U.S. citie

    Rearing broilers as mixed or single-sex: relevance to performance, coefficient of variation, and flock uniformity

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    With known variation in performance between male and female broilers and the fact that sourcing single-sex birds for use in research is becoming increasingly difficult, it becomes important to determine the effect of rearing method with male and female broilers on between-pen variation and body weight (BW ) uniformity. We evaluated the performance response of broilers reared as single or mixed-sex to standard and reduced crude protein (CP ) diets. The study was designed as a 2 £ 3 factorial arrangement of treatments consisting of 672 Cobb-500 broilers assigned to 48-floor pens with 6 treatments, 8 replicates, and 14 birds per pen. The factors were rearing method (male singlesex, female single-sex, or equally mixed-sex) and dietary CP level (standard or reduced). For the overall period of the trial (d 0−35) there was a significant effect (P FI ) and feed conversion ratio (FCR ). There was also a significant interaction between rearing method and CP level for BWG during d 0 to 35 (P P P

    Water Splitting Photovoltaic-Photoelectrochemical GaAs/InGaAsP - WO3/BiVO4 Tandem Cell with Extremely Thin Absorber Photoanode Structure

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    We demonstrate highly efficient solar hydrogen generation via water splitting by photovoltaicphotoelectrochemical (PV-PEC) tandem device based on GaAs/InGaAsP (PV cell) and WO3/BiVO4 core/shell nanorods (PEC cell). We utilized extremely thin absorber (ETA) concept to design the WO3/BiVO4 core/shell heterojunction nanorods and obtained the highest efficiencies of photo-induced charge carriers generation, separation and transfer that are possible for the WO3/BiVO4 material combination. The PV-PEC tandem shows stable water splitting photocurrent of 6.56 mA cm-2 under standard AM1.5G solar light that corresponds to the record solar-to-hydrogen (STH) conversion efficiency of 8.1%
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