I remember[ed] reading a story on a brain-inspired integrated mechanism for energy-delivery and cooling in (experimental) new computer chips:
The human brain packs phenomenal computing power into a tiny space and uses only 20 watts of energy - an efficiency IBM is keen to match.
Its new "redox flow" system pumps an electrolyte "blood" through a computer, carrying power in and taking heat out. [...]
"The human brain is 10,000 times more dense and efficient than any computer today.
"That's possible because it uses only one - extremely efficient - network of capillaries and blood vessels to transport heat and energy - all at the same time."
But as with other biology-inspired stuff, neural networks in particular, what ultimately becomes useful in computer science/engineering may not be that closely related to the way biology actually works.
So what I want to ask here is: are there some detailed mass-and-heat flow analyses for how the brain (of humans or even of other mammals) is actually cooled? How is most of the heat exhausted from the brain? Is it really thorough blood, and then globally through the whole body? Or is mostly a more local process at head level?
I managed to find something about the importance of blood for cooling, but only at whole-body level:
The second influence of the blood flow is that it can enhance heat dissipation from the inside of the body to the environment to maintain a normal body temperature. Theoretical study has shown that if the heat produced in the central areas of the body at rest condition could escape only by tissue conduction, the body temperature would not reach a steady state until it was about 80°C. A lethal temperature would be reached in only 3 hours. During exercise, our body temperature would have typically risen 12°C in 1 hour if no heat were lost by blood flow. Maintaining a core temperature of 37°C during thermal stress or exercise in the body is achieved by increasing the cardiac output by central and local thermoregulation, redistributing heat via the blood flow from the muscle tissue to the skin, and speeding the heat loss to the environment by evaporation of sweat.
So from that I suspect blood is surely important for cooling the brain as well, but still some questions remain, e.g. where does most of the heat from the brain get dumped by the blood? In more layman's terms: is the rest of the body necessary as a radiator for the brain, or is the skull enough for that purpose?
Thanks to a paper cited by AliceD on biology.SE, I also found some anatomical considerations from about two decades ago... which seem to not be very conclusive:
Selective brain cooling (SBC) is understood as a natural mechanism that enables mammals to maintain their brain temperature below the temperature of the rest of the body during states of hyperthermia (Baker 1979). [...]
The question whether SBC also operates in humans, who lack cranial retia mirabilia, has led to an interesting controversy. For some authors (Brengelmann 1987) the copious and constant arterial blood flow to the brain appears sufficient to cool the brain under all conditions. Others (Cabanac 1993) concede that this concept may be correct for the conditions at normothermia, but they propose that an additional brain-directed cooling mechanism becomes effective during hyperthermia. These authors draw attention to vascular arrangements in humans, which permit effects comparable to SBC in "rete species". Cabanac (1993) points to several sites of intimate thermal contact between the arterial and the cooler venous blood, e.g., the internal carotid in the carotid canal, where the artery is tightly surrounded by the venous plexus caroticus and thereafter immersed in the cavernous sinus, and the vertebral arteries surrounded by a plexus of veins where they course through the transverse foramina (see our Fig. 14). Furthermore, Cabanac refers to the high cooling capacity of the skin of the head (particularly rich in sweat glands), whence venous blood, cooled by sweat evaporation, flows via emissary veins towards the brain in hyperthermic situations (Caputa et al. 1978; Cabanac and Brinnel 1985; Deklunder et al. 1991; Hiroshita et al. 1991). An additional loss of heat occurs in the upper airways (Cabanac 1993), including the paranasal sinuses. A direct conductive skin-brain heat exchange has also been considered.
A decade-later paper by Caputa still noted that
The existence of effective SBC in humans has not been proven directly because brain temperature has never been recorded in healthy subjects exposed to hyperthermic conditions.