Bashir Mekki, a Penn State doctoral student in mechanical engineering, focuses on how aircrafts withstand and manage the extreme amount of heat their engines generate.
Currently, heat exchanger design is generally restricted to shapes that have well-known performance characteristics, like pressure drop and heat transfer, where the shapes are very often limited by manufacturability. This also limits the ability to integrate the thermal management system within the confines of the aircraft. Mekki’s research focuses on creating a design tool that generates organic shapes, that can be manufactured using emerging advanced manufacturing capabilities such as additive manufacturing, to enable highly integrated heat exchanger designs.
“I believe this opportunity to do research at NASA facilities and under the guidance of its experts will profoundly enhance my knowledge and experience to achieve my research goals,” Mekki said.
The Doctor doesn’t dislike the cold in this new body.
Heloathesit.
It doesn’t come to him all at once, either. It grows steadily, as the months go by, and late spring turns into summer, then autumn. As this particular season progresses, so does his displeasure.
By December, he’s come to the conclusion that having an internal temperature this high is absolutely ridiculous and pointless, especially when the outside world is now stuck in freezing temperatures that refuse to go back up. Whenever he steps out of a building, any inch of him that is exposed to the frost immediately starts leaking heat, and he’s powerless against the laws of thermodynamics.
“You are such a dork,” Rose points out the first time he goes outside with his new ‘winter outfit’, which comprises (among other things) three layers of clothes, a thick coat, gloves, a scarf and a woollen hat. “You do realise those are ski goggles you’re wearing, right?”
“My eyeballs were freezing,” he replies into his scarf, still rather unhappy about the stinging sensation in his nose and cheekbones, which remain vulnerable to the cold.
For all of her eye rolling at his supposedly ‘dramatic’ reactions, his wife is not faring any better than him whenever they step out in these arctic conditions.
While she will shamelessly mock him for being so sensitive to the drop in temperature, her solution is to use him as a heat pad, going as far as regularly slipping her freezing little hands all the way beneath layers of coat, jumper, shirt and undershirt to press her icy palms over his back.
“You’re so warm,” she tells him, having somehow burrowed her face so efficiently into the crook of his neck that her nose has managed to bypass the tick scarf to be pressed into his skin.
Well, he knows he is, that’s kind of the problem isn’t it?
Not only is he a good fifteen degrees hotter than his warmest incarnation was, but he’s also a whole degree hotter than her body. Maybe it’s all to do with male versus female physiology, or maybe it’s just the universe being an arse.
He suspects the latter.
Rose does love his warm body, constantly encouraging heat transfer between them; and it’s not like she’s simply borrowing his warmth. She’s stealing it, plain and simple.
Sneaking her icy toes between his legs, splaying her frozen hands upon his shoulder blades, ignoring his hisses of discomfort at the sensation, or how his entire body always breaks into shudders, his skin covered in goose-flesh.
“C’mon, t’s not that bad,” she tells him once, while way too many of her digits poke into his shivering flesh like tiny icicles.
“I beg to differ,” he replies. “I’ll have you know that you’ve turned into a proper thermal thief, lately.”
“Yeah?” she asks against his neck, a laughter in her voice. “Gonna call the cops on me?”
We’ve spent some time on the second law of thermodynamics - energy flows naturally from high potential to low, from hot to cold. Most of us have refrigerators or air conditioners in our dwellings - devices which seem to violate this law. They somehow move heat out of a colder space and into a hotter space. So what is going on here?
The short answer is that the refrigerant in these devices acts as a temporary energy storage medium - by some clever manipulation, we can move the refrigerant through a cycle such that at the point it travels through the space we want to cool it absorbs energy, which it needs to dump when it gets to the warmer exhaust space.
Here’s a typical refrigerator schematic.
Refrigerant enters the compressor as vapor. The compressor does work to increase its pressure. Increasing its pressure also increases its temperature, so by the time it hits the condenser it’s relatively hot. In fact, it’s hot enough relative to the surrounding environment that it sheds heat as it flows through the condenser. By the time it leaves, it’s condensed and much cooler, although it’s still at a very high pressure. It goes through an expansion valve from here, which drastically drops both its temperature and pressure. So it enters the evaporator as a low temperature, low pressure liquid. In this state, it is low enough energy that it absorbs energy from the surrounding environment going through the evaporator. When it leaves, it’s a vapor again, ready reenter the compressor and start another cycle.
This works because we are injecting energy into the cycle in the form of work done by the compressor in order to get the refrigerant to a state where the heat it absorbed from the refrigerated space can be dumped to the outside environment.
