Questions tagged [temperature]

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6
votes
3answers
2k views

O-Ring vs flat washer for air seal

I'm interested in whether a flat rubber washer or equivalent is good enough to replace an o-ring in a low pressure application (edit: I meant low pressure differential. My bad.). The reason is that ...
2
votes
1answer
80 views

Is it necessary to consider temperature effect on waling?

Many text book literature on braced excavation mention the necessity to consider additional load due to temperature effect on struts. But nothing is mentioned about waling. Why is this so? Wouldn't ...
1
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1answer
157 views

How to find properties of supercritical CO2 as a working fluid in a system

I'm working on a process flow currently and am using carbon dioxide as the working fluid because of its heat properties and because it's an inert gas. In the reactor that I am designing I'm looking to ...
1
vote
1answer
671 views

Cooling an aluminium plate

My friend and I are currently working on a cloud chamber cooled by the compressor of a deep-freezer. We have built an isolated box that contains the cold pipes of the compressor. The pipes cool down ...
4
votes
2answers
115 views

Got to pour outdoor concrete next week, but forecast is cold. What are my options?

I have to pour outdoor concrete next week. The pour is in two main parts - a 100 mm cover / 2nd pour over a 6 x 3 m area of existing concrete from a 1st rough pour, and the bottom ...
2
votes
1answer
2k views

How to measure a bearing temperature in a pump?

I found that Resistance Temperature Detectors (RTD) are mostly used for bearings, but it's not easy to drill the casing and we need to take a signal out to PLC and LabVIEW. Is there a sensor that can ...
0
votes
1answer
676 views

What type of control system is this? open loop?

Suppose I have a liquid in a container, the type of liquid is such that it expands when its temperature rises. The contrainer is marked with scale to measure the height of liquid expanded. There is a ...
1
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1answer
46 views

How large of an area of the earth's surface would we need to cover in mirrors to negate global warming?

How large of an area of the earth's surface would we need to cover in mirrors to negate current levels of global warming? Let's assume that the reflective component of the mirror is made of aluminium ...
0
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2answers
106 views

Creating a constant internal temperature that is negligible to the external environment

Okay, Hi there Engineers! I am a newbie to this site, and to engineering. So, I wanted to make this post to get all the help I can get. I have been set a task of creating a prototype of the following; ...
0
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1answer
34 views

Lab Equipment for Monitoring Sub Zero Temperatures [closed]

I am doing research on objects frozen with liquid nitrogen then seeing how they thaw. I need to monitor objects temperatures as they thaw. Ideally getting the variance of the external and internal ...
1
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0answers
102 views

How can I define third type boundary condition in ANSYS Mechanical APDL?

I'm currently working on the thermal analysis of a pipe, but i do not know how to define a third type boundary condition on the inner surface. ...
4
votes
1answer
222 views

How to deal with thermal expansion in a city wide heating system?

How to deal with thermal expansion in a city wide heating system? Background: As part of the program to combat pollution in and around Beijing, my adopted city of Zhuozhou (population, over half ...
0
votes
1answer
343 views

Surface in the sun vs. surface in the shade [closed]

What is the difference in temperature between a surface in the sun as supposed to one in the shade and how is it calculated? For instance: What will the temperature be if a metal sheet lies in the ...
13
votes
3answers
8k views

Why does moving air feel cold?

I'm taking a thermodynamics class and had the following question. I was going to ask my professor directly, but it seems like a stupid question with a simple answer, so I thought I'd try my luck here ...
0
votes
1answer
121 views

Is it possible to use air entrainment for air conditioning

I have seen this video pretending to decrease by 5° the temperature inside home using an air-conditioner based on the air entrainment principle (see the video here at 1m6s). EDIT : The video is now ...
4
votes
3answers
162 views

Controlling the temperature with high precision

I need to control the temperature with high precision, and for this task would be good a temperature controller with pt-100 sensor, something like this one PID Temperature Controller ITC-100. As I see ...
7
votes
1answer
10k views

How do train tracks handle really cold weather?

First of all, I'm interested in train track only, not the rolling stock. How are tracks built to cope with really cold weather? An example might be some place in Canada or Siberia. Ice would ...
0
votes
1answer
624 views

What is a transparent material that insulates well? [closed]

I need to create a transparent box that can stay warm inside while in cold temperatures, below 0 degrees, for as long as possible. Glass and plastic are transparent but afaik they don't insulate that ...
1
vote
1answer
237 views

Rapid Cooling System for Commerical Freezer [closed]

I have a bit of an ambitious project on hand and was looking for some advice/ideas. My team and I are working on a project that involves retrofitting a commercial grade freezer (model MasterBilt ...
6
votes
2answers
235 views

Having three heaters on single PCB

I posted this question on electronics SE, but was suggested that I post it here. I basically having three heaters (serpentine pattern) on a PCB (fiberglass board), as the following image shows: The ...
1
vote
0answers
20 views

Three heaters on single PCB [duplicate]

(This is a follow-up to the previous question I posted.) I'm basically trying to control three different tempeartures on a single PCB. It looks like the following: The middle pattern heats up to ...
0
votes
1answer
428 views

At what cold ambient air temperature will power lines fail?

I'm wondering just how cold it would have to be before electric power can no longer flow through overhead power lines. I know power lines generate a certain amount of heat just as a side effect from ...
2
votes
1answer
875 views

Calculating the Fraction of Steam in a Mixture

I have a stream ($10,000$ $m^3/d$) of inert gas and steam. The temperature of the stream is $195$ $^oC$, and the absolute pressure is $1455$ $kPa$. I am trying to find the amount of steam that can ...
1
vote
1answer
2k views

thermal resistance and thermal time constant with ambient temperature

If water at the same temperature is heated with the same heat power source in two different ambient temperatures (one ambient is low and the other ambient is high) then which water sample will reach ...
4
votes
2answers
102 views

Analog PID controller - settings wrt $V_{err}$ - setpoint always higher than room temp

I designed from scratch an analog PID controller to mantain a temperature selected in the range of 60 to 80ºC with a room temp say = 20ºC. The "plant" is a simple 4R7 5 W resistor heated by a PWM-...
3
votes
2answers
1k views

Saturation Temperature of Binary Mixture

I have a binary mixture of water and methane. The system is at 2000kPa and I am trying to find the saturation temperature of the water in the mixture. I know Tsat is a function of partial pressure, ...
4
votes
1answer
407 views

How to extract a building's heat isolation and thermal inertia based on temperature curves?

So imagine we have a house with some isolation and some thermal inertia. This house also has a heating system that turns on (starts heating) when the observed temperature curve goes below some ...
4
votes
1answer
133 views

Should the temperature of a heated metal cone decrease in a plastic enclosure?

Summary A steel cone is heated by a nichrome ribbon to 45–50 °C. I placed a Type K thermocouple over the surface of the metal to measure the heat transferred over the metal surface. The thermocouple ...
3
votes
1answer
94 views

Why do heating elements have lower rated temperatures in vacuums?

I have noticed when examining performance of various heating elements in different atmospheres that in a vacuum maximum temperatures are lower than the in air temperatures. Why is this? (Typical ...
11
votes
1answer
1k views

How does a microbolometer (IR camera) work?

I am currently doing a project which has led me to my first encounter with IR cameras, and I am therefore quite curious as to how they operate. Specifically, I would like to know the following How is ...
6
votes
2answers
4k views

How can I calculate the temperature rise of a circuit board for a given power dissipation and area?

I have a PCB of approximately 4" x 4". It has a single long spiraling trace on it. The trace is 50 mil 4 oz copper, so nominally it's good for something like twenty amps before it overheats. But this ...
5
votes
2answers
3k views

How do I determine the thermal resistance of a metal box?

Suppose I have a sealed enclosure, say this one from Hoffman: The box is 16"x12"x6", made of galvanized steel with a wall thickness of .0635" or .0785" (gauge 16 or 14). I'm planning to put some ...
13
votes
10answers
18k views

Affixing a thermocouple to a surface

I'm looking for advice on how to attach a thermocouple to a metal surface in a fashion that's relatively temperature resistant (more-so than) glue. I've got some very fine gauge wire on hand to make ...
9
votes
1answer
556 views

How do I compute the force required to pierce HDPE?

I have a $2\text{ mm}$ sheet of HDPE at $280-320^{\circ}\text{ F}$. I want to pierce the skin of this sheet with a $2\text{ mm}$-high pin with a surface area of $3.33\text{ mm}^2$. The pin is also ...
5
votes
1answer
510 views

Baffle vs Bottom Temperature Measurement/Control

In an industrial jacketed reactor, we have two temperature probes: one on a baffle the extends down about to the 50% fill line one built into reactor, very close to the bottom valve. When is it ...

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