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@Article{BertoldoJrVlasGenaGued:2015:DyTeMe,
               author = "Bertoldo Junior, Jorge and Vlassov, Valeri Vladimirovich and 
                         Genaro, Gino and Guedes, Ulisses Thadeu Vieira",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "Dynamic test method to determine the capillary limit of axially 
                         grooved heat pipes",
              journal = "Experimental Thermal and Fluid Science",
                 year = "2015",
               volume = "60",
                pages = "290--298",
             keywords = "Dynamic test method, capillary limit, axially grooved heat pipe.",
             abstract = "The usual experimental method to detect heat pipe capillary limit 
                         under different inclinations includes submitting the pipe to a 
                         certain tilt and increasing the heat load at the evaporator zone 
                         until a sudden rise in temperature at this region (dry out) is 
                         observed. According to this method, for each heat load dwell 
                         imposed to the pipe, either the dry out phenomenon is detected or 
                         steady state temperature is achieved. The complete test is time 
                         consuming and the precision of the heat load detection needed to 
                         induce the dry out depends on the power step utilized. In 
                         addition, sometimes the dry out is difficult to detect accurately 
                         in axially grooved heat pipes due to the fact of the liquid phase 
                         is distributed in a non-homogeneous way at the evaporator zone. In 
                         fact, the grooves at the top of the heat pipe tend to dry faster. 
                         At the lower grooves of the evaporator forms a buildup of working 
                         fluid (puddle) due to gravitational effects and thus needing a 
                         higher heat flux to cause the drying. The dynamic method proposed 
                         in this paper to detect dry out in heat pipes consists in applying 
                         a given heat load on the heat pipe, which is initially kept in a 
                         horizontal position on a rotary table equipped with motor with 
                         reducer gearbox and digital inclinometer. After steady state is 
                         reached on the heat pipe, which is leveled horizontally, the table 
                         is driven causing the pipe to adverse tilt slowly until the dry 
                         out occurs. Once dry out initiates, the axial gravity force 
                         component, which is permanently increasing due to table rotation, 
                         provokes the liquid phase accelerated retreating from the 
                         evaporator, including the puddle liquid excess. It assists the 
                         fast overheating onset in the dried zone that in its turn allows a 
                         very clear detection of the dry out event by a temperature sensor. 
                         The pipe is then placed back in the horizontal position. The 
                         proposed test method besides requiring less time to obtain the 
                         capillary limit curve, permits to detect in a more precision way 
                         the exact time when the dry out occurs. The capillary limits 
                         obtained from this method were compared against those obtained 
                         from conventional methods for ammonia two-core axially-grooved 
                         heat pipe. The results show that dynamic test method can be 
                         adopted as an effective alternative to determine capillary limit 
                         for axially grooved heat pipes.",
                  doi = "10.1016/j.expthermflusci.2014.10.002",
                  url = "http://dx.doi.org/10.1016/j.expthermflusci.2014.10.002",
                 issn = "0894-1777",
             language = "en",
           targetfile = "dynamic test.pdf",
        urlaccessdate = "05 dez. 2020"
}


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