17,736 research outputs found
Study of the Effects of Microgroove Geometry on Frost Structure
No full textThe variation in the frost structure on a number of microgrooved brass surfaces is examined through an experimental study. The microgrooved samples are 45 mm x 45 mm in dimension with a broad range of groove dimensions. Frost is grown on these microgrooved surfaces under natural convection for a range of plate temperature (-8 to -18o C) and relative humidity (30-70%) conditions. The frost structure on the microgrooved surfaces, especially at the early stages of frost formation, is found to be significantly affected by the groove geometry (i.e. groove depth and pillar width). Coalescence of the condensed and hence frozen droplets, covering multiple pillars and grooves, is found to occur more frequently on the surfaces with shallow grooves and/or narrow pillars. For surfaces with intermediate groove depth and pillar width, a regular (brick-wall-like) frost pattern on the pillar surface is observed. Thickness and density of frost layer on the microgrooved surfaces are also found to vary with the dimension of the grooves in frost cycles up to 4 hours long. The relationships between frost structure, frost properties, and frost melt-water drainage is discussed, emphasizing the importance of these morphological features
Interview with C. Alfred Frost
No full textC. Alfred Frost narrates his remembrances of being in the United States Army as a sharpshooter and in the Ordnance division during World War II
Frost Growth on Vertical Surfaces with Varying Wettability
No full textFrosting occurs on heat exchangers in heat pumping and refrigeration applications when the surface temperature of the heat exchanger is below the freezing point of water. The accumulation of frost on the heat transfer surface increases pressure drop (fan power) and decreases heat transfer, because the frost layer has a low thermal conductivity much lower than that of the heat exchanger material, and it blocks the air flow. System efficiency is reduced by frost accumulation, and operation is complicated by the need to defrost the heat exchanger. Many factors including air temperature, humidity, and cold plate temperature are known to affect frost growth on heat transfer surfaces. In the present study, a model for frost growth on and densification on flat surfaces is presented. The mathematical model is developed by analytically solving the governing heat and mass diffusion equations with appropriate boundary conditions. For temperature, a convective boundary condition at the frost surface and a fixed cold plate temperature were used. However, for the water-vapor density, the condition at the frost surface is unknown. Unlike earlier saturation and supersaturation models, the current work is based on a specified heat flux obtained experimentally in order to find the density gradient at the surface. From the results, it can be shown that the water-vapor at the frost-air interface is supersaturated.
Frost, Ralph C.
No full textInterview of Ralph Frost for the “Meet the Old Timers” Radio Show on KIEMhttps://digitalcommons.humboldt.edu/old_timers/1004/thumbnail.jp
Artificial frost treatment methods with stone fruits
No full textRoutine application of artificial frost treatment needs a detailed, exact technology, which
would ensure the reliability of the results obtained. Buds being on spurs loose their frost
resistance sooner because of their quick development. According to these results to
examine samples containing both types of buds can lead to significant mistakes.
Considering our experiences it seems that a sample containing 200 buds provides the
reliable correctness. Further increasing of sample size decreases the value of deviation but
it is not proportional to the work needed for the experiment. The following treatments are
suggested: deep dormancy phase: -24 - -26°C, directly after deep dormancy:-21 - -24°C.
beginning of February: -19 - -21°C, two weeks before blossoming -11- -12°C. two -days
before blossoming: -4 - -6°C
Frost Formation on Fan-Supplied Tube-Fin Evaporators: A Visual and Numerical Analysis
No full textThis paper presents an experimental and numerical study to evaluate the thermal-hydraulic performance of light commercial capacity evaporators operating under frosting conditions. A tube-fin heat exchanger was tested on a closed-loop wind-tunnel considering the fan performance. A visual analysis of the frost formation processes was carried out to compare the frost layer morphology in different conditions. A mathematical model was developed and the numerical results were compared with the experimental accumulated mass of frost, air flow rate and cooling capacity, with all the predictions falling within the experimental band of uncertainties. Based on this comparison, a frost density correlation was proposed for a typical range of light commercial refrigeration applications. The results show evaporator cooling capacity reductions up to 40% due to frost formation process. Moreover, the effects of air flow reduction and low conductivity frost layer on the overall thermal resistance were analyzed, when it was found that the former is the main cause of the cooling capacity reduction under frosting conditions
Pictures at Michigan Agricultural College taken about 1888. Now Michigan State College
No full textMAC student, Edward J. Frost created an album of the MAC Campus and buildings from negatives he borrowed from MAC Professor Rolla C. Carpenter
A tree and paths on campus, circa 1888
No full textA tree and paths on campus, circa 1888. The image is from a photo album created by MAC student, Edward J. Frost. He made the prints from negatives he borrowed from MAC Professor Rolla C. Carpenter
Trees next to a path, circa 1888
No full textA view of trees next to a path, circa 1888. The image is from a photo album created by MAC student, Edward J. Frost. He made the prints from negatives he borrowed from MAC Professor Rolla C. Carpenter
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