The human body can deliver lots of work. Consider, for instance, the athlete running a marathon, or the cyclist racing in the Tour de France. We also know that human body temperature is normally 37°C and that usually the environment is cooler, say 20°C. From this we could suggest that there is some resemblance between a heat engine, in which the body is the heat source, and the cooler environment could act as a heat sink. So let's make a few simple calculations to see how closely the body resembles a heat engine. From earlier blogs (see for instance May 6), we know that the efficiency of a heat engine is determined by the temperatures of the heat source (the body temperature, Tbody = 310K) and the heat sink (the environmental temperature, Tsink = 293K): Efficiency = (Tbody -Tsink )/Tbody = (310-293)/310 = 5.5% Thus, based on this temperature difference, the body would be able to achieve only 5.5% efficiency. Fortunately, scientific studies already have estimated the human body's efficiency [Whitt et al.] in other ways. One study reasons that for an average man to produce 75 Watts of power, he will need to breathe about one liter of oxygen per minute. That liter of O2 is combusted in body cells to form carbon dioxide (CO2). It has also been determined that one liter of oxygen generates in this way about 300 Watts of power. Thus, we can conclude that the efficiency of the human "engine" is 75/300 = 25%. What causes the difference between the 5.5% efficiency as calculated above, and the 25% from the combustion determination? The explanation is that the human body cannot be considered a heat engine. The work is not generated in the same way as a steam engine, which directly transforms heat into work and lower-temperature waste heat. Instead, the human body is more like a fuel cell, where chemical energy is transformed into work [Whitt et al]. For this kind of transformation, one obviously cannot use the efficiency formula of a heat engine. Copyright © 2007 William Andrew Publishing, NY
is it possible to construt a heat engine that will not expel heat into the atmosphere
Heat engine utilizes low heat value of oil and also the fuel oil consumption for IC engine usually based on high heat value of oilby Shyam
Friction caused by the movement of cams, cranks and pistons create heat in an engine. The heat from the engine is used to warm radiator water which then is used in the car's heater.
the sun is the external heat engine and the core of the planet is it's internal heating engine.
There are many heat sources located outside of an engine. One of these sources is the sun in the sky.
NO. HUMAN and ANIMAL cannot be considered as a heat engine. the work of BOTH is not generated in the same way as a steam engine which directly transforms heat to work & lower temp. waste heat. instead, human is more like a FUEL CELL. where chemical engines is transformed into work. :)
Humans are considered heat engines by some. Others do not believe that the human body can be considered a heat engine. However, most do on account of the heat production that comes from the human body, as well as, the amount of work the body is constantly doing.
difference schematic diagram between carnot heat engine and heat engine
Heat Engine Heat Engine
The sun provides the heat and energy to support all life on earth, including human.
The heater isn't an extra unit, it is simply pulling heat from the engine and blowing it into the cab. If the engine is not hot the heat will seem like it is not working. If the heat is not working after the engine has warmed up, you may have a fan that doesn't work, or a clogged vent.
yes, it is a heat engine. A heat engine is one that extracts heat energy and converts it to mechanical energy.
Thermal energy is just heat. To convert it to mechanical energy you need some sort of heat engine, like an internal combustion engine or a gas turbine.
A car engine is a heat engine, but there are various types of heat engines outside the realm of car and truck engines.
A heat engine converts thermal energy to mechanical energy. Examples of a heat engine is a refrigerator, heat pump, and carnot cycle. A heat mover transfers heat from one object to another.
is it possible to construt a heat engine that will not expel heat into the atmosphere
Yes. Just don't talk to her