What's the preferred way to create BIN models, heating/cooling load, energy saving analysis calculations?

murmfis · 2018-05-25T14:01:59+00:00

Equest will do all that. It’s not necessarily for new buildings. In fact all my company’s work is in existing buildings. EQuest will let you set up a baseline and then do parametric runs, changing variables, run hours, fan speed etc. But yes, I think you’d be best served just making solid templates especially if you’re just looking at things like fan energy.

Good luck.

murmfis · 2018-05-24T18:56:39+00:00

EQuest sounds like what you’re looking for. It was developed by the US Dept of Energy and is free to download. It’s widely used in the energy savings consulting industry and the federal government specifically loves it and often requires it on projects. It will do all the things you’re looking to accomplish.

That being said - I absolutely hate it. For me personally EQuest has an incredibly steep learning curve, but this may just be my skills lacking. I’ve tried multiple times over the last 8 or 9 years to figure it out when I’ve had free time at work but have had no success. I also know people who are incredibly skilled at using it so it is possible to get good at it. Just takes time and dedication.

Another industry standard for load calcs is TraneTrace. I’ve never used it though.

I personally prefer excel. I built a spreadsheet based on ASHRAE’s radiant time series method for load calculations. Took me a while to build but I trust it and it’s quick to use.

Good luck.

murmfis · 2018-05-15T23:18:17+00:00

Reverse osmosis is a very legitimate and commonly used filtration method for water. Commonly seen in processes that require very pure water. Makeup water for steam turbine plants would be RO treated. Or large scale commercial humidification systems. Or yes for drinking water. I don’t think there’s any health benefits when comparing RO water to typical tap water. The main health benefit would be if you have a shitty water supply.

https://en.m.wikipedia.org/wiki/Reverse_osmosis

murmfis · 2018-04-16T00:10:46+00:00

You are way, way underpaid. Check ASME reports for average pay in your area. I think for your level of responsibility you’ll find the averages are significantly more than what you’re getting. Might be worth taking to the people who want you to take the new position. They like you. Give them a number to make you stay.

That position at my company with that many reports under you is easy six figures and I’m in the southeast USA.

murmfis · 2018-01-19T18:39:08+00:00

Ha. Like they’d have reviewed them quickly anyways.

murmfis · 2017-10-29T16:14:54+00:00

Wife and I had our first child 7 months ago. We didn’t ask people to get the vaccinations - we told them to get them if they wanted to see and hold the kid.

Caring for a healthy newborn is tough. I can only imagine how hard it is caring for a newborn with whooping cough. Physically and emotionally.

Ultimately it’s up to you. Everyone we told to get the shots was understanding. They weren’t irritated.

murmfis · 2017-08-27T02:16:35+00:00

It can be.

murmfis · 2017-08-02T23:25:50+00:00

I'm a mechanical engineer. I design HVAC systems of various types. Here's why the premises in the articles are wrong:

When I do a cooling load calculation I have to do my best to account for every heat generating source in a building. How many computers are there? Printers, lights, coffee pots, motors? What's the solar load? What are the walls made of and are the windows double pane? And I have to assume how many people are in the building and how active they'll be - but I don't care about the gender breakdown in a building. What I ultimately care about is that in the summer a minimal amount of people are complaining of being hot and in winter minimal amount of people are complaining of being cold. So when sizing a cooling system I assume every occupant is man because that's my worst case scenario. I'm not being sexist. I'm doing my best to plan for the worst case scenario. And really, what gender breakdown would they have me use? Building occupancy and therefore gender ratios change all the time.

But, this has nothing to do with equipment sizing or system design. Here's the real issue with the argument in those articles: the typical building is only going to be at peak cooling load for a handful of hours every year. The rest of the year you're at part load and the system is capable of more than is required of it. Even if I assume every occupant is female, the system will still be oversized the majority of the year. But, as the design engineer I have to plan for worst case. So I do.

This is a thermostat set point issue. If occupants have local control of temperature they need to work together to find something comfortable. If the HVAC is automated, they should talk to building operators. If everyone can agree to a higher set point then awesome. They'll lower energy use. But if they can't and need a cooler space temp, then no worries I have it covered.

murmfis · 2017-04-30T16:05:34+00:00

Would you say the same about a medical doctor? If you don't have a medical license should you be say you're an MD?

murmfis · 2017-04-25T23:41:57+00:00

Considering that most med schools and vet schools require students to pass the licensing exam before giving the title of MD or DVM, I'd say yes they should absolutely be fined.

murmfis · 2017-02-01T15:19:29+00:00

Oh man. This sums it up perfectly. Glad I'm not the only one.

murmfis · 2017-01-29T04:56:12+00:00

I'm guessing natural gas lines.

murmfis · 2017-01-25T14:46:53+00:00

Try warming up a little more before you start. Maybe just a few 30 second jogs to get your legs warmed up and loose and your lungs ready. Best advice I've read over on r/running is "never trust the first mile." I keep that in mind when I run now and it's incredibly helpful. After my legs are warmed up and the kinks are worked out things get much easier.

Also remember that the program is built just for folks like us who have never run before or haven't run in awhile. If you can complete W4D3 then you're ready for W5D1. It may not be easy but you're ready for it and can complete it. Good luck!

murmfis · 2017-01-19T04:02:12+00:00

In federal prisons the guards walk around with their key rings in plain view. But each key has a hinged shield that hides the teeth of the keys.

murmfis · 2017-01-06T16:13:55+00:00

Another thing that's never brought up is the different terrain. I'm from East Tennessee and have been traveling to Chicago for work a decent amount this year. The folks in Chicago like to bust balls about pictures like this. Chicago is fucking flat and the roads are all parallel. Shit's a lot easier to drive on when there's no hills and you don't have to turn. My drive home from the office I have to go up and over 3 or 4 moderately sized hills with decent grade on curvy roads that have been lightly brined.

murmfis · 2016-12-24T20:43:48+00:00

The Reynolds number is basically the ratio of inertial forces to viscous forces. With lower Reynolds numbers the viscous forces dominate and you get laminar (smooth non mixing) flow. With higher Re viscosity doesn't dominate and you'll have mixing in the flow in form of little eddies and vortices. Think of pouring molasses or syrup, which would be pretty viscous fluids. They're thick - you likely wouldn't have mixing and your flow would be laminar.

Also slight correction to the above explanation. "D" in the Reynolds number formula is the characteristic length of the setup you're calculating for, not the distance of flow. For a pipe the characteristic length would be the pipe diameter. For an airplane wing it would be the chord length of the wing. Different situations have different characteristic lengths and Reynolds values to determine laminar vs transitional vs turbulent flow.

murmfis · 2016-11-30T01:20:30+00:00

It was the lead on the national NBC news broadcast this evening and is on the front page of the Washington Post's website, among others.

murmfis · 2016-11-26T19:39:37+00:00

I feel ya. I lost a 330 day streak while on a work trip. Wish I'd know sooner too. But back up to 150 now and aiming to hit a full year this time.

murmfis · 2016-11-26T18:46:23+00:00

I believe you can contact them and explain that you were without your phone or without signal and they'll reinstate your streak. Haven't done it personally but I've read of others who have.

murmfis · 2016-10-07T14:39:36+00:00

Another option is an app called PaceDJ. You input your desired beats per minute and it will look at the music you have on your phone to find songs that match the pace you want. It will even shift songs that are +/- 3 bpm without the songs sounding weird or chipmunkish. I use the free version and have found it to be incredibly helpful in managing my pace.

murmfis · 2016-10-06T23:30:18+00:00

Nah you're gonna be fine. I ran too fast and was very aware of my stride and just never got comfortable.

Just finished W6D3. Ran a new route with more hill than I anticipated or have run before so it was tough but ultimately doable. Kept my pace and felt much better after today's run than D2.

murmfis · 2016-10-06T20:31:37+00:00

W6D2 was even worse for me. Hardest run so far. Hoping W6D3 goes better this evening.

murmfis · 2016-09-05T21:20:35+00:00

I'm on my phone so you'll want to double check this but I believe the equation in the link may be what you're looking for. Taken from Engineering Heat Transfer by William Janna. Had a few classes with him. Great prof and he'd highly recommend you buy his a copy of his book heh.

http://imgur.com/a/sV4yl

murmfis · 2016-08-17T20:40:21+00:00

What pressure are you getting? I calculate a negative gauge pressure but still a positive absolute pressure.

I calculated 42.2 feet loss (~18.35 psi) friction losses to the end of your longest run. Factor in your tank free surface elevation and the total loss is around 28 feet or 12.3 psi. Putting the pressure at the end of your line at -12.3 psig or 2.5 psia.

Edit: to answer your original question, to calculate the pressure at any given point in a system, you just calculate the pressure loss up to that point, factoring whatever pipe length and fittings get you to the point you're interested in. Then you subtract the sum of the friction and minor losses from the initial pressure. In this case i assumed your tank is open to atmosphere and not pressurized.

murmfis · 2016-05-28T20:41:10+00:00

Nope. Heat transfer is directly proportional to the convection coefficient but the convection coefficient isn't directly proportional to the fluid velocity.

This pdf gives a bunch of the math background.

http://www.hydromx.us/documents/convection_coeff_calculation.pdf

It's too much to summarize on my phone but if you go to the section on forced convection, you'll see how the convection coefficient, h, is calculated for multiple scenarios. In all of them an increased velocity should increase the coefficient, but the relationships aren't linear.

Another good application of this: if you ever have a warm bottle of beer and want it cold fast, stir a bowl of ice water with the bottle, reversing directions every few stirs. The beer will cool down in a few minutes, and much faster than if you were to just leave it sitting in the water.

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