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Cocurrent and countercurrent heat exchange. A cocurrent heat exchanger is an example of a cocurrent flow exchange mechanism. Two tubes have a liquid flowing in the same direction. One starts off hot at 60 °C (140 °F), the second cold at 20 °C (68 °F). A thermoconductive membrane or an open section allows heat transfer between the two flows.
The effect of this biological heat exchanger is that the internal temperature of the feet is much closer to the ambient temperature, thus reducing heat loss. Penguins also have them in the flippers and nasal passages. Seabirds distill seawater using countercurrent exchange in a so-called salt gland with a rete mirabile. The gland secretes ...
Penguins and many arctic birds use these exchangers to keep their feet at roughly the same temperature as the surrounding ice. This keeps the birds from getting stuck on an ice sheet. Other animals, like the leatherback sea turtle, use the heat exchangers to gather, and retain heat generated by their muscular flippers. [5]
The pre-flight warm-up behavior of a moth. Insect thermoregulation is the process whereby insects maintain body temperatures within certain boundaries.Insects have traditionally been considered as poikilotherms (animals in which body temperature is variable and dependent on ambient temperature) as opposed to being homeothermic (animals that maintain a stable internal body temperature ...
Within the rete, the warm and cold blood flow past each other in opposite directions through thin vessels to maximise the heat transferred. This mechanism is called a counter-current heat exchanger. In addition to the rete mirabile in its gills, the opah also has a rete in the blood supply to its brain and eyes.
More specifically, arterial and venous blood vessels are organized to bypass the countercurrent heat exchange occurring in the upper portion of a bird’s legs. Countercurrent heat exchange involves arrangements of blood vessels that allow heat to transfer from warm arterial blood to cooler venous blood travelling to the body’s core. Through ...
The number of transfer units (NTU) method is used to calculate the rate of heat transfer in heat exchangers (especially parallel flow, counter current, and cross-flow exchangers) when there is insufficient information to calculate the log mean temperature difference (LMTD). Alternatively, this method is useful for determining the expected heat ...
Many ectotherms exploit the heat produced by endotherms by sharing their nests and burrows. For example, mammal burrows are used by geckos and seabird burrows by Australian tiger snakes and New Zealand tuatara. [13] Termites create high and regulated temperatures in their mounds, and this is exploited by some species of lizards, snakes and ...