Probability

Sigma3/Epsilon

After the morning meal Dirck roamed around the ballome as if movement could speed Zinni’s course to its lowest declination, cooling it down enough to resume work outside, at least until Zeta‘s position elevated enough to start the cycle again.  He’d long since disposed of his old anoia uniform for some simple lightweight clothes he’d found on the trade table at the SD but his hair had gotten horrifically long and he felt like a slob. He glanced at ‘Merama, working on the latest information for the Barterboard.

“Hey, ‘Merama, how ‘bout a haircut?”

She didn’t even look up. “I can’t. I traded off the clippers before you and your father got back from Verdaris.”

Various implications lurked behind her works and his gut tightened.  “So you can’t cut our hair anymore?”

“Not until we can afford another pair.”

“Holy holocubes, ‘Merama—.“ He stopped in mid-gripe cringing at another self-imposed reminder of his part in Creena’s disappearance. Eventually new frustrations invaded his thoughts until, tired of pacing, he sat down by the comcon and called up their account. He smiled as he viewed the latest transaction:  =C20C= from Jen Brightstar for a “wager.” Deven and ‘Merama had posted The Regionists' Guide to Edible Plants on the bulletin board four days before, and already they’d brought in =C700C=. 

And that wasn’t all.  Win had found him several water-tight containers and every day he filled at least three and took them to the SD. So far he hadn’t had any trouble getting =C150C= per liter. Their total for all trading was =C15700C= and growing. 

That was the good news.

The bad news was that his father had finally settled on a preliminary design for the heat exchanger. His original expectations had been too optimistic. They’d be lucky if they could maintain an inside temperature of 37C/99F, which represented a delta-T, or difference in temperature, of 64C/115F from the average outdoor High Opps temperature, which sounded impressive except the majority was coming from the ballome’s climate control system. How much they could depend on it not to degrade when its limits of 66C/150F were exceeded was unknown with it possible it could fail entirely, in which case they’d be dead.

Even the slight but critical reduction the heat exchanger could achieve would require a duty cycle of a hundred percent, meaning it would be running constantly, which of course required more power plus put more stress on the components. They’d use hydrated ammonia as the working fluid in what was called an absorption heat removal system. But even with the compromised temperatures, they had to have a compressor. The system couldn’t keep up with the relentless heat load without it.

So far the listing of parts and components they needed had over a hundred line items and amounted to an expected cost of over =C60000C=s.  At the rate they were rolling in, thirty days before High Opps, which would barely allow time for the actual construction, they’d have approximately =C32500C=. 

He had no idea how they’d make up the difference. Another =C225C's= came in as he watched, from a liter of water and one Guide. Maybe sales would pick up. And maybe they wouldn’t.

‘Merapa had decided to accumulate enough credits to buy the compressor first. There was only one at the SD and he was afraid someone else would get it first. Win had hidden it in the back, but that was still no guarantee. The remaining parts were relatively simple.

‘Merapa had explained how the system worked so many times he knew it by heart. It was all a matter of transferring heat energy from one place to another. Liquid ammonia would absorb the heat in a network of pipes. The hot liquid would flow to larger tubing, where reduced pressure would allow it to evaporate, storing the energy in a gaseous state. A fan would cool the tubing, the working fluid would change phases again by condensing back to a liquid, and this time release energy which the fan would dissipate. Then the compressor would re-pressurize the liquid, and it would start the cycle again. 

It was deceptively simple. And awesomely hard. In fact, their predicament illustrated why the interface between science and engineering, i.e., theory and application, had tried men’s ingenuity since time began with there typically a wide gap between the two.

At least he was going to meet Win when he got off work at the SD. He wasn’t sure what they were going to do but it was still a break and visiting with someone around his own age sounded great, even though it would definitely cut into what was supposed to be his sleepzone. He knew Win had gone to a Miran academy, had worked at the SD since the settlement was organized, and that was it.

Undoubtedly it would be an interesting evening.