Wednesday, June 29, 2011

Shake-down for the heat exchanger

We've tested the heat exchanger and it passed with flying colors.

Alex was on the roof of the Bevill Building here at UA, which gave us a drop of about 7 m (a little less than the drop we have at Hengill). The hose could only get 0.3 L per second through the exchanger. Our flow at the field site will be higher than that, but the exchanger should be able to handle it. Now we have to take it apart and figure out the cheapest way to get it to Iceland.

Tuesday, June 28, 2011

Heat exchanger assembled (almost)!

Check it out! In a flurry of activity this afternoon, Chau and Benstead assembled the heat exchanger in two halves. It's all ready to carry outside - 12 connections and it will be in one piece and ready for flow and pressure testing. That will happen in the morning - watch out for a video.

Heat exchanger under construction

Here are some shots of the heat exchanger starting to come together in the Benstead lab. Here, Jon and Chau are getting ready to link up the 72 steel tubes to the manifolds. Note that Philip the Engineer is conspicuously absent for the construction phase...

We should be ready for a flow test in the next 24 hours. Watch this space. Then it will all have to be taken apart and shipped out to Iceland for the planned October deployment.

Tuesday, June 14, 2011

June Fieldwork

What do you get if you put two engineers and a stream together? A dam, of course!

We were joined in June by Drs. Pauline and Philip Johnson from the University of Alabama's Department of Civil, Construction and Environmental Engineering. Here they are busy doing some geomorphic work at the top of our warm stream (Stream 8). This is the eventual site for the heat exchanger that will warm water for the thermal manipulation of the adjacent cold stream.

The engineers are joined in this picture by Alex Huryn and Dan Nelson, the Ph.D. student who is working on the warming experiment. Philip is holding one of the manifolds for the heat exchanger. The whole thing will need to be submerged eventually. Hence, the need for some kind of dam.

In addition to planning for the construction and installation of the heat exchanger (set for September 2011), we also did a lot of fieldwork in Streams 7 and OH2, the two streams under intensive study as part of the warming experiment. Here's a shot of some benthic metabolism measurements under way at OH2.

Another task was to continue collecting reaeration data from Streams 7 and OH2. Here's a shot of our set-up for delivering a solution of rhodamine and SF6 to the streams using a gas bag and metering pump.

All in all, the June trip was a great success. We brought 500 lbs of gear to Iceland (for $110!), got a lot of fieldwork done and brought several months-worth of samples home safely. We even managed to get the dry shipper all the way home on the plane - quite a victory after some miserable failures.

Now we're gearing up for the very busy summer ahead. The undergraduate assistants arrive on 15 June and work on the landscape temperature gradient will start soon after. Let's hope for some pleasant weather!