| ??? 01/10/05 21:57 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#84696 - Heat Transfer Rates and Efficiency Responding to: ???'s previous message |
Steve,
Based on some of the info in previous posts of this thread, I've got following numbers - A 600 gram block of copper raised cooled from 40 deg C to -40 deg C needs to get rid of 4.5 kcal. One kcal = 4187 watt-sec, so 70 watt cooler (100 % efficient) can cool the copper in about 4 and a half minutes. That's not far off the 7 minute number you measured going full tilt when it's recognized a Peltier is notoriously inefficient (and gets worse with increasing delta T). I'd say you've hit the minimum settling time. Bruce |
| Topic | Author | Date |
| OT Step responses | 01/01/70 00:00 | |
| Step respons | 01/01/70 00:00 | |
| Happy with PID | 01/01/70 00:00 | |
| Re Happy with PID | 01/01/70 00:00 | |
| more details | 01/01/70 00:00 | |
| Making Use of Three Sensors | 01/01/70 00:00 | |
| Heat pipe? | 01/01/70 00:00 | |
| Minimizing Settling Time | 01/01/70 00:00 | |
| Timing | 01/01/70 00:00 | |
| Heat Transfer Rates and Efficiency | 01/01/70 00:00 | |
| Nice estimation | 01/01/70 00:00 | |
| Worked that out | 01/01/70 00:00 | |
| Segments of different PID parameters | 01/01/70 00:00 | |
| integrating cap | 01/01/70 00:00 | |
| Abruptly changing... | 01/01/70 00:00 | |
| Exaclty | 01/01/70 00:00 | |
| Have you Read Above? | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
| Maybe this can help? | 01/01/70 00:00 | |
| Interesting | 01/01/70 00:00 | |
| Reference | 01/01/70 00:00 | |
RE: Reference | 01/01/70 00:00 |