Welcome to the Solar Collector
Brainstorming and Development Page!


 

Home

Hot Air Collector

Hot Water Project 1

Hot Water & Space Heating

Solar Electric

Solar Construction 101

FAQs

Best Collectors

Simply Solar
Register Calendar Latest Topics
 
 
 


Reply
  Author   Comment  
matlocc

Registered:
Posts: 66
Reply with quote  #1 
Ok, so the kids figured the panels are 2.4 cubic /ft. The anemometer is showing 530 ft/min  so does that mean the air is changing 220 times a minute?  530/2.4  not sure what I am doing wrong.

gbwillson

Avatar / Picture

Registered:
Posts: 2,224
Reply with quote  #2 
Normally we don't calculate the actual CF inside a collector, as it doesn't figure in performance numbers. Although a smaller space inside a collector will heat up marginally faster, it also means the airflow is closer to the cold glazing. We DO, however, calculate the CFM for the airflow. To do that you need to convert the LFM(linear feet per minute). Here is a link to calculate your own numbers. Just be sure to enter the proper duct size.

http://www.calculatoredge.com/optical%20engg/air%20flow.htm


As you can see below, there is roughly 46CFM of air passing through the collector. So divide the air passing through by the space inside the collector to find the exchange rate. 46.25 / 2.4 = 19.27 air changes per minute.  

Greg in MN
Airflow screenshot.jpeg 














matlocc

Registered:
Posts: 66
Reply with quote  #3 
Thanks Greg.  I figured that out after I posted.  I start with the inside volume just to see how they are with measuring and simple math!  Then they get an idea of how much air they are heating without fans and then we go from there.  Without fans they are getting about 3-5 percent effiecency. Then they work up.
gbwillson

Avatar / Picture

Registered:
Posts: 2,224
Reply with quote  #4 
I like to focus more on BTU output than efficiency. I have several small electric space heaters that know the BTU output, so I have a specific output for perspective and comparison. BTU output is also easier and quicker to calculate. 

Greg in MN
Garage_Hermit

Avatar / Picture

Registered:
Posts: 2,240
Reply with quote  #5 
Hi, matlocc,

that efficiency does not look too right to me -
you might find this link of use...

https://www.builditsolar.com/References/Measurements/CollectorPerformance.htm

Enjoy !

G_H

__________________
(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilĂ " unless talking musical instruments...
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.

 

web statistics