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<article dtd-version="3.0" article-type="Invited Methods Article - JoVE Produced Video">
  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher">jove</journal-id>
      <journal-id journal-id-type="email">editorial-office@jove.com</journal-id>
      <journal-title-group>
        <journal-title>Journal of Visualized Experiments</journal-title>
      </journal-title-group>
      <issn pub-type="ppub">1940-087X</issn>
      <issn pub-type="epub"></issn>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="publisher-id">JoVE57437</article-id>
      <article-id pub-id-type="manuscript">JoVE57437</article-id>
      <article-categories>
        <subj-group subj-group-type="Article Type">
          <subject>Invited Methods Article - JoVE Produced Video</subject>
        </subj-group>
        <subj-group subj-group-type="Category">
          <subject>JoVE Engineering</subject>
        </subj-group>
        <subj-group subj-group-type="Classification">
          <subject>Fluid Mechanics and Thermodynamics</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Measurements of local instantaneous convective heat transfer in a pipe - single and two phase flow</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author" corresp="yes">
          <role content-type="1" />
          <name>
            <surname>Fershtman</surname>
            <given-names>Adam</given-names>
            <prefix>Mr.</prefix>
          </name>
          <email>adamfersh@gmail.com</email>
          <xref ref-type="aff" rid="aff1" />
        </contrib>
        <contrib contrib-type="author">
          <role content-type="2" />
          <name>
            <surname>Barnea</surname>
            <given-names>Dvora</given-names>
          </name>
          <email>dbarnea@eng.tau.ac.il</email>
          <xref ref-type="aff" rid="aff2" />
        </contrib>
        <contrib contrib-type="author">
          <role content-type="3" />
          <name>
            <surname>Shemer</surname>
            <given-names>Lev</given-names>
          </name>
          <email>shemer@eng.tau.ac.il</email>
          <xref ref-type="aff" rid="aff3" />
        </contrib>
        <contrib contrib-type="editor">
          <name>
            <surname>Navani</surname>
            <given-names>Dipesh</given-names>
          </name>
          <degrees>Ph.D.</degrees>
          <email>dipesh.n@jove.com</email>
          <xref ref-type="aff" rid="aff4" />
        </contrib>
        <aff id="aff1">
          <institution>Tel Aviv University Iby and Aladar Fleischman Faculty of Engineering</institution>
          <institution content-type="position">PhD student</institution>
          <addr-line content-type="addrline1">Ramt aviv</addr-line>
          <country>ISRAEL</country>
          <addr-line content-type="city">Tel aviv</addr-line>
          <addr-line content-type="state">Israel</addr-line>
          <addr-line content-type="zipcode">6997801</addr-line>
          <phone content-type="primary">97236408535</phone>
          <institution>Tel Aviv University Iby and Aladar Fleischman Faculty of Engineering</institution>
        </aff>
        <aff id="aff2">
          <institution>Tel Aviv University Iby and Aladar Fleischman Faculty of Engineering</institution>
          <institution content-type="dept">Mechanical Engineering</institution>
          <addr-line content-type="addrline1">Ramat aviv</addr-line>
          <country>ISRAEL</country>
          <addr-line content-type="city">Tel aviv</addr-line>
          <addr-line content-type="state">Tel aviv</addr-line>
          <addr-line content-type="zipcode">6997801</addr-line>
        </aff>
        <aff id="aff3">
          <institution>Tel Aviv University Iby and Aladar Fleischman Faculty of Engineering</institution>
          <institution content-type="dept">Mechanical Engineering</institution>
          <addr-line content-type="addrline1">Ramat aviv</addr-line>
          <country>ISRAEL</country>
          <addr-line content-type="city">Tel aviv</addr-line>
          <addr-line content-type="state">Tel aviv</addr-line>
          <addr-line content-type="zipcode">6997801</addr-line>
        </aff>
        <aff id="aff4">
          <institution>JoVE</institution>
          <addr-line>1 Alewife Center</addr-line>
          <addr-line>Suite 200</addr-line>
          <addr-line>Cambridge, MA  02140</addr-line>
          <country>UNITED STATES</country>
        </aff>
      </contrib-group>
      <history>
        <date date-type="received">
          <day>05</day>
          <month>10</month>
          <year>2017</year>
        </date>
        <date date-type="rev-recd">
          <day>09</day>
          <month>01</month>
          <year>2018</year>
        </date>
        <date date-type="rev-recd">
          <day>19</day>
          <month>12</month>
          <year>2017</year>
        </date>
        <date date-type="accepted">
          <day>10</day>
          <month>01</month>
          <year>2018</year>
        </date>
      </history>
      <abstract>
        <p>This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer coefficient as a function of the liquid flow rate in a transparent pipe. With certain amendments, the approach is extended to gas-liquid flows, with a particular emphasis on the effect of a single elongated (Taylor) air bubble on heat transfer enhancement. A non-invasive thermography technique is applied to measure the instantaneous temperature of a thin metal foil heated electrically. The foil is glued to cover a narrow slot cut in the pipe. The thermal inertia of the foil is small enough to detect the variation in the instantaneous foil temperature. The test section can be moved along the pipe and is long enough to cover a considerable part of the growing thermal boundary layer.
At the beginning of each experimental run, a steady state with a constant water flow rate and heat flux to the foil is attained and serves as the reference. The Taylor bubble is then injected into the pipe. The heat transfer coefficient variations due to the passage of a Taylor bubble propagating in a vertical pipe is measured as function of the distance of the measuring point from the bottom of the moving Taylor bubble. Thus the results represent the local heat transfer coefficients. Multiple independent runs preformed under identical conditions allow accumulating sufficient data to calculate reliable ensemble-averaged results on the transient convective heat transfer. In order to perform this in a frame of reference moving with the bubble, the location of the bubble along the pipe has to be known at all times. Detailed description of measurements of the length and of the translational velocity of the Taylor bubbles by optical probes is presented.
</p>
      </abstract>
      <kwd-group>
        <kwd>Local instantaneous convective heat transfer</kwd>
        <kwd>thermography</kwd>
        <kwd>optical sensor</kwd>
        <kwd>ensemble averaging</kwd>
        <kwd>Taylor bubble</kwd>
      </kwd-group>
      <funding-group />
      <counts>
        <fig-count count="0" />
      </counts>
      <custom-meta-group>
        <custom-meta>
          <meta-name>Please indicate whether this article will be Standard Access or Open Access. </meta-name>
          <meta-value>Standard Access (US$2,400);</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>Please indicate the &lt;b&gt; full address&lt;/b&gt; at which this article will be &lt;b&gt;filmed&lt;/b&gt;.</meta-name>
          <meta-value>Tel-aviv University, Wolfson Engineering building, room 270</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>Is all of the written text in your manuscript original (neither plagiarized nor self-plagiarized)? If using previously published figures, are re-use permissions from the previous publishers obtained and cited in the figure legends?</meta-name>
          <meta-value>Yes.</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>Black and White Image Count</meta-name>
          <meta-value>0</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>Color Image Count</meta-name>
          <meta-value>0</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>Acquisitions Editor</meta-name>
          <meta-value>jialan zhang</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>Assistant who entered lead</meta-name>
          <meta-value>Kaitlin Cleary</meta-value>
        </custom-meta>
      </custom-meta-group>
    </article-meta>
  </front>
  <body>
    <fig>
      <graphic xlink:href="Figure1.tif" xmlns:xlink="http://www.w3.org/1999/xlink" />
    </fig>
    <fig>
      <graphic xlink:href="Figure2.tif" xmlns:xlink="http://www.w3.org/1999/xlink" />
    </fig>
    <fig>
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    </fig>
    <fig>
      <graphic xlink:href="Figure4.tif" xmlns:xlink="http://www.w3.org/1999/xlink" />
    </fig>
    <table-wrap>
      <label>Materials Table</label>
      <graphic xlink:href="JoVE_Materials.xls" xmlns:xlink="http://www.w3.org/1999/xlink" />
    </table-wrap>
    <fig>
      <label>Figure 2</label>
      <graphic xlink:href="Fig2.tif" xmlns:xlink="http://www.w3.org/1999/xlink" />
    </fig>
    <fig>
      <label>Figure 5</label>
      <graphic xlink:href="Figure5.tif" xmlns:xlink="http://www.w3.org/1999/xlink" />
    </fig>
  </body>
</article>