Wednesday, April 29, 2015

HVAC Lab–Energy Question

Question:

I am confused by the units and figures in the E_airflow portion of question 2.  For the calculation in row 32, "Energy brought in by ventilation airflow, Ev:", the only related equation I could find gives E_airflow = m x [0.24T + W(0.45T + 1061)].  I have already calculated m.  I imagine that T is temperature, but is it temperature difference, indoor temperature, or outdoor temperature?  I see that the answer should have units of btu/h.  So far with m, I have lb/h.  How do I get from lb to btu, and what is this W for?  Also, are the rest of the values in this equation constants, or do they need to be modified for our figures?

Response:

  • If you look at the Parameter Definitions above you’ll find the meaings of T, W, Q and other terms used in the lab.  The subscripts define indoor and outdoor conditions.
  • You are given the equation in the instructions to calculate the energy.  Note that it’s units are BTU/hr.

Sunday, April 26, 2015

IAQ and HVAC Lab - Flow Rate Question

Question

For the IAQ and HVAQ Lab, specifically regarding Question 2, no value is given in the PDF for Qe (Exhaust Flow Rate). In Question 1, the Excel sheet said to assume that Qv=Qe= 800 m3/h. Is this true for all questions, that Qv = Qe?
So in Question 2, does the assumption continue that Qv = Qe? Or is there a relationship with the Total Air Flow Rate of 7200 m3/h that must be considered? Does Qv + Qe have to equal Qt? If this is the case, how can both Qv and Qe equal 800 m3/h in the first question?

Answer

Please see the second from the bottom paragraph on page one – algebra in there governs the relationship between Qv and Qe.


Thursday, April 23, 2015

Warnings on Lab-4 HVAC

Hello everyone,
A few announcements about spots in the Lab where you need to be careful.

  1. We were discussing units for L-4 during the Sec-61. There's a typo in units for Emission RATE ECO2/V (both in the PDF and XLS Quest1 cell I13. The correct unit is ppm/(h*ppl) - makes sense to have 1/h for a rate. In the Sec-61 class we thought a typo was in I29, and we were wrong. I just corrected the BbLearn template, as of Thu 4/23 20:09.
  2. If you like to make a unit analysis, remember that kwh is a jargon for kW*h, a unit of energy. My PECO bill also uses kWh, no multiplication operator inside!
  3. EER is a Coefficient Of Performance, it compares Energy vs. Energy. In the industry it is often used unitless, but the 'unit' for it is BTU/(W*h) - Energy/Energy. Keep it in mind when you see it in the cell I20 of Quest2. You will need to use EER in your calcs!!! In addition to the Lab there's a good chance the Final Assessment will have a question about EER.
  4. With that said simply follow the PDF instruction and you will get it done all correct.
  5. BIG WARNING Quest3: in the columns answer what you are asked, read the columns' heading WORD-TO-WORD and answer what is asked there. The cost of a wrong answer there could be  easily 15 pts!
Good luck and remember you have ALL the data and parameters in the PDF, Quests' themselves ("Please determine ...") and the Gray Blocks.


HVAC Discussions

Hi, It's your friendly neighborhood discussion grader signing in with my weekly blog post.  Overall, well done on the HVAC discussions, and I think everyone has figured out the key to doing well in these discussions by now.  I would like to make a few general comments:

-  As most of you noticed, the future of HVAC design is in making buildings more efficient and technologically advanced.

- The most tricky part of things like net-zero buildings, smart homes, etc.  is to increase efficiency without sacrificing comfort or safety.

- Another large concentration in HVAC is Indoor Air Quality, which is becoming a huge concern in large cities where pollution is a problem.

As I have said about previous discussions, only a handful of you will end up practicing HVAC engineering in your career.  I would argue that these discussions are more important to the people not interested in that particular topic, because they force you to build some knowledge base, at least to the point where you can understand what your HVAC engineer is talking about.  Please make an effort when doing these discussions to glean some understanding of the topic you are reading about.  If you learn even just one thing from each discussion, you will grow and become a much more rounded engineer.

Thanks, and Happy Discussing!

-Brad

Tuesday, April 21, 2015

Week-4 - Rec Center Tour - Lab Locations and Times

This coming week we’ll be touring the Rec Center AND having time in the lab to address the calculation assignment of the week.  You should plan to be involved the whole two hours of your lab period.  The sessions in Main-301 and Randel-326 are to help you with the lab calculations.

Note that we will meet outside the East entrance to the Papadakis Integrated Sciences Building (inside if raining).  Here’s a map showing where we’ll meet and where we’ll go.

Wear flat shoes (NOT heels) – we’ll walk on sensitive surfaces.

Time & Location

image

Sunday, April 19, 2015

Hydrology Discussions

Hello,

Regarding last week's discussion post on hydrology, I have a few general comments for the class:

Overall, very well done.  It seems as though most students are making an effort to read and comprehend the articles they are choosing, and to make intelligent comments about them.

Remember that the main purpose of these discussions as a whole is to introduce you briefly to all of the main topics in the CAEE department.  Not every topic will interest you, and that is ok.  Try to gain a basic understanding of the topics you are not interested in, and don't be afraid to dig a little deeper into the ones that you do like.

If there is something you don't understand in your article, it can only help you to try researching and finding a little more information.

One thing to take away from this is that the work that Civil Engineers do is among the most taken for granted of any profession.  Supplying potable water, removing waste, protecting entire cities from flooding, etc.  are all incredible accomplishments that the public accept as normal, without a thought to how difficult a feat they truly are.

Thanks, and keep up the good work!

-Brad

Saturday, April 18, 2015

Water Reduction–Meanings

Question


I have a couple questions about the CAEE 201 lab from this week. I am wondering what "Potable Water Reduction" and "Storm Water Reduction" mean conceptually. I have talked to a few students, and none of us seem to be able to figure out or find online what those phrases mean so that we can figure out how to do the calculations.

Response

Potable water = Drinkable water = water bought from the city
Storm water reduction = water that doesn’t go into the city sewers that would have without your prevention system, in this case the cistern and it’s associated engineering components.

Supplemental Question

In the lab, we were told that the potable water reduction value and storm water reduction value should be different numbers. However, I keep getting the same value (but different percentages) for both. My thought process was that potable water reduction is water we don't have to buy from the city (what we collected in the cistern), and that storm water reduction is water that doesn't go into city sewers because of the cistern (what we collected in the cistern). With that, it makes sense that I am getting the same value, but since we were told in lab that they should be different I assume that I am missing something. I would appreciate if you could clarify that they should/should not be the same value.


4/22/2015 Update

I need to apologize to those students who asked this question.  Thanks to another student not being satisfied with the answers I'd given I checked and found that indeed the potable water purchase reduction produces exactly the same amount of storm water overflow reduction.  The percentages will be different, but the actual numbers ARE the same.

This does make sense since the water that goes into flushing the toilets does not go down the drain.

I've used this lab for multiple years and never been asked the question before so I never thought it through and never noticed the identity.

My suggestion below of using boundary conditions is still often helpful, but was misleading in this case.  That's why I've put lines through the answer. 

Response - See Above 4/22/2015

It’s often useful to think of a “boundary condition” example when trying to address this sort of problem.  Think of the following:
  • There is no rain whatsoever.
    • Would the city have to buy water in this case?
    • Would there be any overflow in this case?
Hopefully that will help you think through the answer to your question.

Update 4/20/2015
It was pointed out after lecture that this boundary case isn't as illustrative as desirable.  So, think of another one.

  • The amount of rain that falls every day is exactly what is needed by the toilets
    • In this case there would be no water purchased from the city (Maximum Reduction) AND no overflow and therefore a maximum of storm water reduction.
    • If the rainfall increases there will be no change in the water purchased for toilet flushing (purchase remains at zero).  There will, however, be an increase in the overflow and thus a decrease in storm water reduction.

Writing Water Budget / Hydrology Memo

Hello everyone,
The Hydro Lab is a great opportunity to write a Memo on an actual project of Evaluating Rain-harvesting Cistern Performance. Compose your Memos in a passive voice. For the Hydro lab you can, and I encourage to, avoid the word "Lab" entirely, including the title. You were not doing a Lab, you were in reality evaluating how the cistern work and ho it benefits the environment and Drexel's balance books!
Good luck,
Walter 

Individual Feedback on Lab-1 In a File Returned by the TA

Several students have been unclear how to access the files that the TA’s have graded and returned via BbLearn.  Here are instructions that worked on the BbLearn before:.

  • Open the course in BbLearn
  • Click on Grades in the left column
  • Click on the title of assignment - e.g. "Week-3 Lab Structures"
  • You’ll see the attached file in lower right under the small heading "File Name". It can be also located in a sub-menu "Feedback to Learner" (that's actually how I see it on my TA interface) 
    • Click on it to see it
    • You can download it by clicking on the small icon with a downward arrow in top dark bar - 2nd from right
    • For Lab-1 sec-60 the filename starts with "grd_", for sec-61 with "Wk-1_Lab".
    • When open the file, browse through each page, that's where we usually leave feedback.

Thursday, April 16, 2015

Lab 3 Hydro - Harvested Rain Volume

Hello all,

Just a reminder that pls be careful with units when getting the volume of the harvested rain.

Cheer,
Walter

Sunday, April 12, 2015

Discussion 1

Hello!

Welcome to CAEE-201! My name is Brad, and I will be grading your weekly discussions this term.  I would like to start by apologizing for my tardiness in grading the first set of discussions.  In the future, expect them to be graded by Thursday every week.  If you have any questions about the discussions, feel free to email me at bjd66@drexel.edu.  I am also more than willing to answer, to the best of my ability, any general questions you may have about what life is like for a CAEE student at Drexel.

As far as the discussion posts go, make sure to read the grading rubric over for future posts.  It is very easy to get a 15 every time, as many of you will.  Just make sure to read and comment on two separate articles related to the weekly topic, as well as comment on at least three of your classmates' posts.  Please post these as actual comments on the other students posts, so that they are more easily visible to the students you are providing the comments to.

I would like to encourage you to make it a point to learn something new every week in these discussions.  If you come across a term or topic you don't quite understand, dig a little deeper and try to figure out exactly what it means.  Increasing your knowledge base now can help a lot in your future endeavors.  Good luck, and have fun!

-Brad

Tuesday, April 7, 2015

Lab-1 Question

Question

“For question 5 is there a specific formula I need to know? If so what is it?”

Response

Both Part “a” and Part “b” ask you to use basic physics reasoning.  We belief you can derive the necessary equation given an understanding of what’s happening.

For Part “b” the way’ I approach it is to imagine a cubic foot of air.  Can I figure out how much it weighs?  Can I figure out how many BTU’s it take to heat that cubic foot 1DegF?  How many to heat it 20DegF?  How many CF of air would it take to convey 8,000 BTU?

You should be able to check your answer using units.

Sunday, April 5, 2015

Lab-2– Revit –Times and Locations

This week’s lab will again be located in the CAEE CadLab in CAT-167.  It’s on the ground floor in the Southeast corner of the building.  CAT is the building to the North of Ludlow (where the food trucks are located)  - Link to Google Maps

Familiarity – Email to Skip Lab Session

If you are already competent with Revit you may send me an email (James.Mitchell@Drexel.edu) BEFORE the lab time saying you know Revit and don’t need to attend the lab.  I’ll mark you present for the lab.

Times

Because there are only a limited number of computers in the lab we’re splitting each section in half, so each comes for only 1 hour.  You may exchange with a student from another section, but except as noted below please do not come at a time different than the one to which you’re assigned.

Note that section 061 is much bigger than Section 060 so some students from 061 may come to the 060 times with a reasonable chance of finding a place.  Those officially in the section will have priority if we exceed the capacity of the room.

Section 060 9:00-11:00

  • A-L  9:00
  • M-Z  10:00

Section 061 11:00-1:00

  • A-L  11:00
  • M-Z 12:00
Revit

We’ll be using the program Revit in the lab.  You’re welcome to download it for your laptop for free from http://students.autodesk.com.

  • It’s a 3GB download and a 5GB Install
  • You’ll need to register with Autodesk
  • It’s for Windows Machines only
  • Be aware you’ll need to copy the files you create in the lab to yourself via thumbdrive, email, DropBox or something similar.  Your files will probably be erased from the machines.
  • Also be aware that files created in a newer version of Revit are NOT openable in older versions.

Thursday, April 2, 2015

An example of a well-structured Memo

More help on memo writing can be found with search terms 'OWL Purdue engineering writing' and 'PSU engineering writing'. Memo is a type of Correspondence, search for this type once you are on the Purdue or PSU site.
The following Memo was altered by a meaningless array of words. In your memos please feel free to use underline and bold typeface to emphasize important messages. USE PARAGRAPHS!
*** Please consult the blog post for further details of a Memo content***
========================================================================

TO: Dr. [Lecturer of the Week], PE
FROM: ----- -------------
DATE: Month Day, 2015
SUBJECT: Measurements in Civil, Architectural and Environmental Engineering Lab

This is your PURPOSE section:
The purpose of this lab was to calculate and [compare] the _________, ________, __________ [stresses], and to calculate the _________ [factor] of the ____________________________.
This is your DETAILS SUPPORTING section:
This lab began with the ______________________. Various dimensions of the ___________ were measured with a laser tape and recorded. The ________ of the ___________ was 2”x 21”, the depth of the [sub-element 1] was 62.6”. There were a total of 5 [items #2] [spanning] the length of the __________. A provided [instrument, protocol, blueprints] showed six _________ of 1234.5’ each.
The [initial stress] was greater than the [thermal boiling freezing other stress], which was greater than the [absolute value of the capacity]. The calculated [post-initial] stress was 1.62*106 psf, the [post-post-initial] stress was 1.4*106 psf, the [thermal freezing resistance] was 1.5*105 psf. All [post-initial] [conductancies] were calculated by dividing the moment by the area of the [rotor] and the depth of the [lake] by zero. The [pre-initial] load moment was 2.2*105 ft*lbs, the [pre-post-initial] mass and acceleration were 2.46*106 ft*lbs/s. The stress due to [thermal excitation] is proportional to the change in temperature and the [another property of a material may go here]. It was [recorded, calculated, received] as 1.0*104 psi at 1234oF.
The [value] is a number representing the relative [property of a structure, characteristic of an assembly] when [loaded]. It is equal to the material capacity minus the [some property, quality, description], all over the [post-presumptive-quality #4]. A [negative] [value in the results] means the [assembly #2] will not [satisfy Standards ASTM-123.456-000], even without [pre-treatment]. A factor of [a thousand] would be [acceptable, safe, and controllable] but have no margin for [economical consideration]. The [rating, evaluating, manufacturing] factor for the [assembly #2] was 1233.4 [times]. A value of more than 987 [times] is above a satisfactory value; and it has a [high, best, acceptable] [safety, durability] [rating].
This is your IMPLICATIONS section:
Examples of the themes that are appropriate to use in here: The [exercise, process, structure] proved _________ is suitable [useful, beneficial] for __________. The [structure] is [safe] for [standard] use. If the [structure] were ___________ or the _________ were to [fail] on a day of significant heat change, the [structure] can ________.
This is your LIMITATIONS section:

    There was a [adjective] limitation in [obtaining the dimensions, for example]. The width and mass of the __________ were estimated and not verifiable measured. The instrument had last calibration 11 months ago, and is near its yearly certification test. The software used has been known in the State of CA to cause heartbreaks. Those limitations [affected, compromised] __________. [list and discuss other assumptions, short cuts, questionable data, vintage data, extrapolations, limited visibility, etc.] 

Memo Writing For Lab Reports

Here is a blog post from a previous version of CAEE-201 addressing what you want to consider when writing a Memo for this course, or any other course.  The length, of course, will vary from once course to another.