 in this segment what we're going to do is we're going to take a look at the question why study heat transfer and if you recall what we said is that heat transfer is basically energy in transit due to a temperature difference. So all the processes that we're going to be looking at will involve a temperature difference and we'll be able to hopefully illustrate how heat transfers taking place in each of those. Now what we're going to do we're going to take a look at a number of different systems and I'm just going to list them out and then we're going to go through and take a look at them and describe them. Okay so those are the things we're going to look at and what I hope to be able to show you is that heat transfer exists all around us and consequently it has a significant application into our modern lives. So what we're going to be doing we're going to be looking at heat transfer within residential buildings. We're going to look at heat transfer within residential electrical systems. We'll take a look at what I call everyday living places where heat transfer has an impact in our everyday lives. We'll take a look at refrigeration systems that we have in our homes. Lots of heat transfer there. Laptop computers, they generate a lot of heat, they dissipate a lot of heat. Anybody who has a laptop in their lap obviously knows that they generate heat so we're going to take a look at that and then finally we'll conclude by looking at transportation systems. So this is a bit of a G-Wiz lecture. The purpose of it is to provide you with a little bit of motivation and background for why we're studying heat transfer. So let's begin. So we're beginning with residential buildings and here we have a hot water boiler in a house and we're going to zoom in on the area where the energy is being added. So here what we're looking at these are planes where burning natural gas and the heat that is generated is used to heat a boiler. Water is circulated using a circulation pump and then that goes through a manifold system and through pipes that extend throughout the house. Here you can see one of the pipes going through one of the floorboards and it goes up and then it goes into hot water radiators and so through natural convection which we'll study in this course that is how the heat is transferred from the liquid through fins into the room and that's what heats it. Now where does that heat go? Well eventually it goes out into the atmosphere and here you can see some homes and a lot of the heat loss obviously is coming through the windows that's one of the areas where we have the lowest resistance to heat flow and consequently that is heat transfer in residential buildings. Another one we're going to take a look at let's now look at residential electrical systems and so this begins with the power that is coming to our homes from power plants that could be very very far away but what happens is that power is at a high voltage it needs to be reduced and there you can see a transformer on a pole. If you have underground lines that's another transformer again the transformer has got hot. It comes into our homes into a distribution panel there you can see the ground fault circuit interrupts are a little hotter. We have a stove clock, a telephone, they're all generating heat, a cable splitter, a power bar, a cable box with your TV, a photo frame they generate a lot of heat as you can see on the right. A ground fault circuit interrupt plug on the left and a dimmer switch on the right and then these are interior wall plugs and exterior wall plugs you can see on the exterior we lose heat to the outside so that's a quick look at electrical systems. Now a lot of those systems are being cooled naturally and consequently there is no forced convection providing the cooling but cooling of electronic systems is very very important and we will be looking at that throughout this course. The next segment that we're going to look at is what I call everyday living so let's take a look at that. Now everyday living we're going to begin with the biological a professor that is in shape is a happy professor this is me on a stair stepper and you're going to see a 45 minute workout compacted into a number short number of seconds. You can see as I go into the workout you're looking at it every five minutes so watch what happens to my body I'm getting pretty hot you can see that I'm sweating a lot so my body is regulating the temperature by perspiring and then that provides cooling to my body and as I go on and on you can see that my head is getting hotter as are my hands there I'm done I'm stretching a little bit and there you can see the byproduct of exercise so I'm very happy we have hot water systems in our home so there you can see hot water coming out of the tap you change it to cold all of a sudden the water goes black so actually it's just cold and with the infrared camera you can see this is something that I like to do every day I do like coffee I have to admit so here is an automatic espresso maker and you can see the hot espresso coming into the cup lots of heat transferring these things if you've ever taken one apart a number of different boilers and you take that hot coffee and here we're pouring hot coffee into cold milk so the milk is on the bottom and there you can see the beautiful natural convection cells that are forming we will study those in this course they're not as perfect as Rayleigh Bernard convection cells that we will look at but nonetheless they are convection cells and eventually the coffee and milk comes to a uniform temperature and there is the coffee cup ready to be consumed so that is heat transfer in everyday living the next thing that we're going to take a look at are refrigeration systems household refrigeration used to be done by bringing in a block of ice and you put it in what they called the ice box and then through the development of the refrigeration cycle using different types of working fluids which I cover in my thermodynamics course and we have the convenience of having refrigeration in our home so this is something that happened long long ago but anyways let's take a look at those refrigeration systems we're going to look at two different types we'll look at what I call a free convection refrigerator and a forced convection refrigerator so let's begin with the free convection and so there you can see the compressor at the bottom and the heat rejection in this cycle is through coils that are on the back of the refrigerator and those coils are connected to wires that are essentially acting as fins and then you have natural convective heat transfer so those coils are hot and there when you look on the IR camera you can see the compressor is very hot you have the hot refrigerant going up and then coming through the coils and that's where it rejects heat to the room now more modern refrigerators they've compacted everything into the bottom and we use forced convection so there is a fan in these systems so there you can see the IR on the left the compressor is hot and then the coils are on the right and there you can see the fan right in the middle and what it does is it forces air to go over the coils where we're rejecting the heat from the refrigerant which then becomes part of this cycle for refrigeration so lots of heat transfer in your refrigerator the next thing we're going to look at electronics a lot of cooling is required in electronics and and so we're going to take a little bit of a history review of laptop computers so let's take a look at the IR signature of laptops this is from 1998 a micron transport xke you can see the thermal signature sony with a p3 processor from 99 another sony another p3 from 2001 another sony this one with a pentium m from 2005 here's another sony this one always operates hot for some reason with an i7 and then here's another sony that does not operate as hot so those are sonys here are some apples apple manages the heat in a very different way it brings it out behind the keyboard as you can see in these images so that's a macbook pro and then a macbook pro 15 with a retina display and and you can see where the heat is dissipated and this is an older del but i like this one 2002 for the reason that i have a motherboard and so we can take a look at what's going on on the inside and there i zoom in on the processor and if you look at the processor it is attached to a heat dissipation system there's a heat pipe which then moves over to some fins and then there is fans on the other side of the fins that result in force convective heat transferred to remove the heat from the processor and so that was a heat pipe that you're looking at and we will be looking at at the basis of heat pipes when we study boiling and condensation in this course and we'll also be looking at fins so all of those things we're going to be looking at in this course and cooling of laptops as we put more and more transistors onto the processors becomes more and more of an issue and consequently there's tons and tons of heat transfer in any kind of electronic systems as we could see with the laptops the final thing we're going to look at is transportation so transportation we're going to begin this is a Chevy pickup truck you can see the engine is hot the exhaust pipe is hot this is looking at the engine on the inside of the engine with the engine running that's the radiator hose going to the engine block and a lot of heat the only thing that's cool in there is the air conditioning compressor which is on the top in the middle as well as the inlet air duct you can see that that's a little cooler but everything else is very very hot including the alternator looking where does that energy go while it propels the car and it also goes out through the exhaust and so there you can see the exhaust pipe products of combustion or heat co2 and water vapors we could see there these are vehicles in transit and so here we can see there are different thermal signatures for many different types of vehicles there you have a big semi trailer and it has its exhaust pipes when you look at the exhaust from the back sometimes you see dual exhaust manifold sometimes you see just a single exhaust manifold with the hot spot on the back of the car and then these are cars in traffic so on the left we have stop and go traffic on the right we have free flow and you can see in stop and go that the cars are getting hot because they don't have as as good of a convective heat transfer as they've been designed for and that's why they're operating very hot as they drive by and stop and go now this is an aircraft this is a dash eight landing in Calgary and you can see the turboprop engine a lot of heat there and then on the left we can see the blade and touchdown and then finally this is another aircraft with a gas turbine engines coming in and you can see the gas turbine engines are very very hot a lot of thermal systems are in there thermodynamics fluid mechanics heat transfer and consequently that is a very very important area of keeping the gas turbine blades cool as we'll see here this is the blade from a gas turbine engine and what you're looking at here this is the leading edge of the gas turbine blade looking at it from the end you can see the cross section and so it's a very curved shape the other thing to notice there is a bit of a bluish white coating and that would be a coating to protect it from the high temperatures that would be encountered within the exhaust gas stream of the gas turbine engine and the other thing to notice is that there are a number of ports on the bottom of the blade where it would go in to the engine itself and compressed air from the compressor would be used and imported through that ducting system and then it would come out through these small ports there's some on the leading edge there's some up on the tip of the blade some towards the trailing edge and then even on the tip you can see there are more ports there those are used for cooling the blade due to the hot combustion gases and and that is the gas turbine blade so there we go you can see a lot of heat transfer exists in systems that we have in our everyday lives be it transportation be it things within residential be it everyday living so hopefully that provides you with motivation to focus and study on heat transfer throughout this course under the realization that it is very very important to our lives everyday living we have enormous amounts of heat transfer in it and I only focused on some of the things that we encounter daily there are also industrial processes with enormous amounts of heat transfer and and consequently but the principles are all the same and any of the principles that we develop for these systems would apply to industrial systems as well so I hope you enjoy that you can come back and watch it if you need motivation while you're studying for exams or something like that