MERM Chapter 33 question

The solution to problem 33.6 makes no sense to me at all. I used the ASHRAE table for ammonia to get the enthalpies but it wasn't even close to the enthalpies in the solution. Please tell me what table they were using to get their enthalpies. They talk about interpolating in the table but fail to tell you which table they are talking about.

Does anyone know?

JoeysVee said:

The solution to problem 33.6 makes no sense to me at all. I used the ASHRAE table for ammonia to get the enthalpies but it wasn't even close to the enthalpies in the solution. Please tell me what table they were using to get their enthalpies. They talk about interpolating in the table but fail to tell you which table they are talking about.
Does anyone know?

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You are right. I think this problem is based on the Amonia tables from an earlier edition of the MERM.

Joey,

I sent you a message. Please check it out and respond.

Thanks,

Mike.

MikeR said:

Joey,
I sent you a message. Please check it out and respond.

Thanks,

Mike.

Click to expand...

I have responded! Thanks Mike! arty-smiley-048:

I have the same question, thought I would revive this old thread to see if anybody had figured out what's the deal with this question. I've found the Ammonia tables but can't figure out why it was solved the way it was on the MERM. Please, somebody help!!!! Thanks!

Pedro.

Can anybody tell me whether or not i can write with pencil in MERM book while preparing. I know i cannot write anything during the exam in the books.. I am taking it in NY

kvarshne said:

Can anybody tell me whether or not i can write with pencil in MERM book while preparing. I know i cannot write anything during the exam in the books.. I am taking it in NY

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Do not write in pencil.

kvarshne,

I responded to your other post, but I thought I would respond to one of your statements here. It is perfectly acceptable to write in the exam book. However, nothing written in the exam book will be scored or be considered when scoring your exam.

So, no word from anybody about question 33.6 in the MERM. Btw, I'm using the 11th edition.

@eldude: here is MY solution

ASHRAE ammonia (717) p-h diagram and FE handbook (Reverse Rankine pg. 78)

COP =(h2-h3)/(h2-h1)=(305-(-260))/(305-200) = 5.38

Correction: based on ASHRAE 2005 – R717 diagram (see NCEES HVAC sample and sol 501)

COP=(750-135)/(750-635)= 5.34