When we measure cooling its called a BTU. Why is it a BRITISH Thermal Unit?
368316
Not really sure about this one. It sounds like it originated in Britian but I can't find references to that. The US uses it  when discussing energy and the British uses it too but to a lesser degree. Sorry can't give a more fulfilling answer.\n\nCheck out.\n\nhttp://en.wikipedia.org/wiki/British_thermal_unit\n\nI did more checking and found this other site. Do I get the best answer award?!\n\nhttp://www.wisegeek.com/what-is-a-btu.htm
526487
Hey dummy - the US gallon is actually the older of the two measurements. Great Britain changed what was then called the "Liquid Gallon" (now known as the "US Gallon") into what is now the "Imperial Gallon" or the "Ale Gallon" in order to have an easily calculable relationship with the pound (weight, not money). Read all about it here before you make a fool of yourself again.\n http://en.wikipedia.org/wiki/Gallon\nThe United States didn't change the gallon, Great Britain changed it!!!
911579
It comes from "libra" which describes the Roman unit of mass that is equal to the pound.  A lot of these abbreviations tend to come from Roman/Latin roots which explains why they seem so weird.
391108
Are you mixing up a thermocouple for a thermal-switch. In all the applications mentioned above a thermal switch is used. The thermocouple is a lab device which is used to measure relative temperatures. A thermal-switch is an absolute device which either opens or closes at a given temperature.\n\nA thermal-couple is used to measure continuously the temperature while performing a experiment. It is usually attached to a component or surface being tested.\nThe results are compared to a controlled known temperature surface.\nUsually when testing to meet UL underwriters lab testing.
109470
This ain't my forte, but here goes.\n\nAdiabatic expansion is like what my freezer and air conditioner use to cool things off.  They take a pressurized gas and let it expand, which drops its temperature.  Then they let this low-temperature stuff suck up the heat in my Ben & Jerry's or in my house.  If you've ever discharged a CO2 fire extinguisher or used a can of compressed air to clean your computer, the CO2 is so cold it condenses the water in the atmosphere or the air on your computer is very cold.\n\nIsothermal means the temperature stays the same.  So if your gas expanded and it didn't get colder, something else went on to provide the heat to keep the temperature the same.  \n\nMaking heat is work, in physics terminology, so the isothermal expansion required more work than the adiabatic expansion.
492587
In air conditioning, 1 ton = 12,000 BTU cooling power
213043
I think it is a measurement device for flow (either measuring air or using pneumatic pressure). Some information on transmitters....
601553
a unit raise of temperature of a unit water in a unit time is called a degree of temperature.(i think answer is this.)
338000
I only had time to do the first one, btu the answer is \ne-2.  Check your email for the work.
790311
To get the most out of your room air conditioner, you'll need to consider the size of the unit that best suits your needs.\nThe cooling capacity of room air conditioners is measured in British thermal units per hour, or Btu/h. To figure out the maximum cooling capacity for a room, you will first need to calculate the size of the room where the air conditioner will be placed.\nTo do this, simply multiply the width of the room by the length of the room.  Use the following information and formulars to help you with calculating your air conditioning requirements:\n\n\nHeat Load\n\nThe amount of heat generated is known as the heat gain or heat load. Heat is measured in either British Thermal Units (BTU) or Kilowatts (KW). 1KW is equivalent to 3412BTUs.  The heat load depends on a number of factors, by taking into account those that apply in your circumstances and adding them together a reasonably accurate measure of the total heat can be calculated. Factors include: \n\nThe floor area of the room\n The size and position of windows, and whether they have blinds or shades \nThe number of room occupants (if any) \nThe heat generated by equipment \nThe heat generated by lighting \nArea of Room\n\nThe amount of cooling required depends on the area of the room. To calculate the area in square metres:\n\n\nRoom Area BTU = Length (m) x Width (m) x 337\n\n\nWindow Size and Position\n\nIf, your room has no windows, you can ignore this part of the calculation. If, however there are windows you need to take the size and orientation into account.\n\n\nSouth Window BTU = South Facing window Length (m) x Width (m) x 870\nNorth Window BTU = North Facing windows Length (m) x Width (m) x 165\nIf there are no blinds on the windows multiply the result(s) by 1.5.\nAdd together all the BTUs for the windows.\n\nWindows BTU = South Window(s) BTU + North Window(s) BTU\n\n\nOccupants\n\nYou will have to take that into account people who normally working in the space. The heat output is around 400 BTU per person.  \n\nTotal Occupant BTU = Number of occupants x 400\n\n\nEquipment\n\nClearly most heat in a room is generated by the equipment. This is trickier to calculate that you might think. The wattage on equipment is the maximum power consumption rating, the actual power consumed may be less. However it is probably safer to overestimate the wattage than underestimate it.\n\n\nEquipment BTU = Total wattage for all equipment x 3.5\n\n\nLighting\n\nTake the total wattage of the lighting and multiply by 4.25.\n\n\nLighting BTU = Total wattage for all lighting x 4.25\n\n\nTotal Cooling Required\n\nAdd all the BTUs together.\n\nTotal Heat Load = Room Area BTU + Windows BTU + Total Occupant BTU + Equipment BTU + Lighting BTU\n\nThis is the amount of cooling required so you need one or more air conditioning units to handle that amount of heat.\n\n--------------------\n\nGeneral thumb rule \n\n100 sqr ft area with roof height of 9 - 10 ft will need 1 Ton AC unit.
89918
Convection and conduction are both important.  Radiation is negligible.  Heat is transported from the inside air to the refrigerant, and from the refrigerant to the outside air, through two heat exchangers.  In each exchanger, heat is transferred by a mixture of convection and conduction* between refrigerant and heat exchanger tubing, conduction through the walls of the tubing, and convection* (which may be forced by a fan) between the tubing and the air.  \n*Some may disagree with my interpretation of which kinds of heat transfer dominate each of these phases; it's a judgment call.  If most of the heat transfer is due to motion of the fluid (refrigerant or air) it's convection; if not it's conduction.
1142478
It is the SI unit of energy. It is also the unit for work in physics (force times distance). But I don't get the rest of your question.
772330
You just need a few basics to estimate things.\n\n1.  6000 watts is 6 BTU/sec.\n2. 1 BTU heats 1 lb of water 1 degree F\n3. 1 gallon of water weighs 8.3 lbs.\n4. A nominal natural convection heat transfer coefficient is 1 BTU/(ft^2 * hr * deg F)\n\nIf you barrel is well insulated, just use the above (except 4) and you will see that 25 gallons will heat at 0.027 deg F per second.  \n\nIf you arent insulated, you need to use the heat transfer to see what portion of the 6000 watts is lost as the temperature rises.  You can readily do this in general form and the result should be an exponentially asymptotic temperature.
942206
for all of the Amdahl Millenium mainframes the power consumption is between 8.1 - 13.4 KVA with a heat of 26.7 - 36.54 KBTU/HR \n\nKVA = A unit of apparent power, equal to 1,000 volt-amperes; the mathematical product of the volts and amperes in an electrical circuit.\n\nBTU =  The quantity of heat necessary to raise the temperature of one pound of water one degree Fahrenheit from 58.5 to 59.5 degrees Fahrenheit under standard pressure of 30 inches of mercury at or near its point of maximum density. One Btu equals 252 calories, (gram), 778 foot-pounds, 1,055 joules or 0.293 watt hours.
107432
Thermal insulation is the reduction of thermal conduction to a point where it reduces the flow of energy from one system to another.  In laymans terms, you have a flow of energy (usually in Btu/s or J/s aka Watts), between two systems of different temperatures.  By isolating the systems from each other with an insulator, you are slowing the transfer of heat and energy from one system to another. \nThat is the goal of an insulator - reducing (slowing) the rate of heat transfer.
662957
Many people are often confused about power and energy.\nLet's start from the beginning, with some basic equations:\n\nEnergy = Force * distance\n\nFor a mass m moving at a speed v, the energy E is:\n\nE = 0.5 * m * v * v\n\nEnergy can be measured in Joules (J) or British Thermal units (BTU). 1 BTU is equal to roughly 1055 Joules. If a 2100 pound car is travelling at 60miles/hour, the energy is about 342600 Joules or 325 BTUs. This is the same amount of energy required to accelerate the car from 0 to 60 miles/hour on level pavement. This is independent of acceleration, it doesn't matter if it takes 6 seconds or 60 seconds, it's the same amount of energy.Energy is always conserved, meaning it can't created or destroyed, it can\nonly change form.\n\nPower = rate of energy\n\nPower can be measured in Watts (W) or Horsepower (HP). 1 HP is the same as 746 Watts.\n\nPower, unlike energy, is not always conserved. If we have a system where energy is flowing at a constant rate, then power is conserved, meaning the power in is equal to the power out. For standard cars, power from the engine is delivered to the wheels through a transmission. There are some losses due to the transmission, air conditioner, alternator, and other systems, but this is not considered a significant loss. If the air conditioner is turned off, your headlights are off, and you have a manual\ntransmission, the losses will be not more than a few percent. Automatic transmissions only increase losses.\n\nThe gear ratio is a transmission does not change power output. Remember,power is conserved in this case. There might be some slight change in power loss for different gear ratios, but for the most part, it's insignificant.\n\nSince we know power is the rate of energy, we can divide the energy calculated above by the time required to produce the energy. If it takes your car 6 seconds to go from 0 to 60 miles/hour, then the power is about 57000 Watts or 76.6 HP. Keep in mind, this is the average power, it doesn't\ntell us the power at any time during the acceleration. We would need detailed speed measurements from start to finish to calculate that.\n\nGiven these numbers, I would guess the engine is capable of producing 150 HP or more. How did I come up with that number? Internal combustion engines, like gasoline, Diesel, and even turbines, do not have a flat power curve. The power output is zero at zero RPM and increases more or less\nlinearly until some peak. In stock gasoline engines, the peak power is at 5000-6000 RPM or so. As a rule of thumb, the peak is generally 1000 RPM below red line. So if you could run your engine at 1000 RPM below red line,\nthen you could achieve near peak performance. If watch your tachometer, I would guess that the RPM averages much less than that, maybe even half.\nThat's why you are getting only half of the power the engine is capable of producing.\n\nRPM, power and torque are all related. Torque is simply power divided by RPM. The power out of a transmission is the same as the power in (minus small losses), but the RPM is different depending on the gear ratio. If the output shaft spins at half the speed of the input, then the output torque is double that of the input. RPM doesn't really matter in the end as far as power is concerned, remember, power is conserved. Changing gear ratios does not change the power, it only affects torque and RPM. It's easier to start with calculate power and work out RPM and torque if you need it. You can do it the other way, but it's easy to make mistakes.\n\nThe reason most cars have a transmission at all is because gasoline engines cannot produce torque over a wide range of RPM, particularly at zero RPM.Diesel electric locomotives and subways do not have transmissions with variable gear ratios because they use electric traction motors instead of\ntransmissions. Electric motors can produce torque over a wide range, even at zero RPM. This is known as the stall torque
544081
ok remember that freon or r134 are used in AC but is not like it is a substance that stays cold... you to compress it in order to make it liquid and then it absorves heat and evaporates completing the cycle... if you are looking for a sort of system that will make something stay cool.. .hmmm man it is called Air Conditioned