Thermodynamics is basically concerned with heat transfer, energy transfer and conversion between heat and work and is also applied to describe phase change of a substance, such as condensation and evaporation.
1.1 Determination of steam quality
Saturated water is water in the condition in which any amount of energy put into the water or absorbed by the water can result in water-steam, two phase mixture, formed. In this case, latent heat, enthalpy of evaporation, is referred to as the energy required to change water into steam. Steam quality is referred to the percentage weight of the steam in a mixture of steam and water, that is, dry saturated steam contains no water. (Babcock & Wilcox Co., 2007).
Saturated steam, which is steam at equilibrium with water, can only exit at specific pressure and corresponding temperature. Provided any change of temperature and pressure is made, the condition of steam will be impacted. For example, if the temperature is decreased, or increasing the pressure, there will be amount of steam condensed and then wet steam formed. Otherwise, a large pressure drop can bring saturated steam into superheated steam. The relationship of water and steam can be found from temperature – entropy diagram.
It can be realised from the T-S diagram, that the condition of being steam-water mixture is at somewhere between that of saturated water and that of saturated steam. If any change of pressure or temperature of the water-steam mixture can lead the mixture to be saturated water or saturated steam.
Obviously, when there is amount of moisture present in steam, it will contribute to the energy consumed or heat utilised which rises the temperature of the moisture to that of the steam. (Babcock & Wilcox Co., ...
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...be moved by the difference in density of the air. In this case, the convection is called natural convection. The heat transfer rate of forced convection is basically higher than that of natural convection. It causes that the surface temperature in forced convection is lower than that in natural convection.
As previous mention, the heat transfer due to radiation is different from convection as well as conduction. The heat transfer due to radiation can be considered as a result of the changes in the electronic configurations of the atoms or molecules. (Cengel, 2007) owing to the fact that the heat transfer due to radiation does not require the presence of medium of passing or transferring heat, it is faster than the heat transfer due to convection. For example, in the experiment, the heat transfer due to radiation occurred in both of the part 1 and part 2.
Water is heated in the first container (1) which produces steam. The steam carries heat, called latent heat. A pump on the wall of the first container (1) pumps the steam into the second container (2). The steam from the first container (1) heats the syrup and boils it, creating sugar crystals, in the second container (2), using up the latent heat in the steam from the first container (1). The evaporating syrup creates it's own steam, with latent heat as well. A pump on the opposite wall of the second container, (2), pumps the latent heat in the steam into the third container (3).
Two equations were used in this experiment to determine the initial temperature of the hot water. The first equation
Theory: Steam distillation uses boiling point to separate organic liquid and water. The organic compound must be immiscible with water, have a high vapor pressure at 100˚C, and may decompose before boiling point is reached. Steam distillation increases the vapor pressure of water more than the vapor pressure of the organic compound as temperature rises to reach the boiling point of the mixture which is a little less than 100 ˚C (boiling point of water) but a lot less than 254 ˚C (boiling point of eugenol). Since the liquids are immiscible, the total vapor pressure only depends on the vapor pressure of each component added together and not the mole fraction leading to a higher vapor pressure which corresponds to the lower boiling point.
Materials of different types will exhibit varied changes in temperature when transferred the same amount of heat. This variation is a result of the difference in properties displayed from one material to another, known as "heat capacity." Every substance has a variable, positive valued heat capacity that represents the amount of heat required to initiate a specific temperature change. (Hechinger, page 1) For ideal gases, there are heat capacities at constant volume and constant pressure given by:
The data which was collected in Procedure A was able to produce a relatively straight line. Even though this did have few straying points, there was a positive correlation. This lab was able to support Newton’s Law of Heating and Cooling.
Although Black’s discovery of carbon dioxide was said to lay the foundation for modern chemistry, it wasn’t the only discovery he is credited for. He was the first to conclude that heat and temperature were two different things. Black used water as a universal substance to show that heat is energy, in which may be transported through moving and colliding molecules and the idea that temperature is the measurement of the average motion or kinetic energy of the molecules. He demonstrated this with a bucket of ice monitored by temperature constantly. The ice continually melted, but the temperature remained constant. Black is also well known for his discovery of latent heat, the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature. Latent heat was con be expressed in two ways: the heat can be absorbed if the change involves solid to liquid or liquid to gas or the heat can be released if the change involves gas to liquid or liquid to solid. Black took this idea and developed “specific heat”, in which is defined as the measured amount of heat required to raise the temperature of a substance by a specified number of degrees.
on how long it takes to heat up. If we heat a large volume of water it
Conduction, convection and radiation are the three methods through which heat can be transferred from one place to another. The (www.hyperphysics.com) first method is the conduction through which heat can be transferred from one object to another object. This process is defined as the heat is transmitted from one to another by the interaction of the atoms and the molecules. The atoms and the molecules of the body are physically attached to each other and one part of the body is at higher temperature to the other part or the body, the heat begins to transfer. A simple experiment through which conduction can be understood easily is as follows. First of all, take a metallic rod of any length. Hold the rod in the hand or at any stand made up of the insulator so that the heat does not transfer to the stand. Heat up the one end of the rod with the help of the spirit lamp. After sometime, touch the other end of the end, the other end of the becomes heated too and the temperature of the other end of the rod has also increased. Although only one end of the rod is heated with the spirit lamp, but the other end of the rod has also been heated. This is represents that the heat has been transferred from one end of the rod to the other end of the rod without heating it from the other end. So, the transformation of the heat is taking place. This process is called the conduction. Conduction is a process which is lead by the free electrons. As the conduction happens occurs only in the metallic materials, the reason for it is that the metals has the free electrons and they can move freely from one part of the body to another part of the body. These electrons are not bounded by the nucleus so, they can move ea...
Conduction, convection and radiation are the three methods through which heat can be transferred from one place to another. The (www.hyperphysics.com) first method is the conduction through which heat can be transferred from one object to another object. This process is defined as the heat is transmitted from one to another by the interaction of the atoms and the molecules. The atoms and the molecules of the body are physically attached to each other and one part of the body is at higher temperature to the other part or the body, the heat begins to transfer. A simple experiment through which conduction can be understood easily is as follows. First of all, take a metallic rod of any length. Hold the rod in the hand or at any stand made up of the insulator so that the heat does not transfer to the stand. Heat up the one end of the rod with the help of the spirit lamp. After sometime, touch the other end of the end, the other end of the becomes heated too and the temperature of the other end of the rod has also increased. Although only one end of the rod is heated with the spirit lamp, but the other end of the rod has also been heated. This is represents that the heat has been transferred from one end of the rod to the other end of the rod without heating it from the other end. So, the transformation of the heat is taking place. This process is called the conduction. Conduction is a process which is lead by the free electrons. As the conduction happens occurs only in the metallic materials, the reason for it is that the metals has the free electrons and they can move freely from one part of the body to another part of the body. These electrons are not bounded by the nucleus so, they can move easily. And when the temperature of the ...
The comparison between the vapour compression and vapour absorption systems are given in Table 1
Difference of the feedwater heater is 5°C. The rest of the steam is reheated to
When high temperature steam is reduced in pressure it becomes super-heated steam. The temperature of super-heated steam is higher than its saturation temperature and the steam is dry. Superheated steam is hotter than the temperature it takes to boil water at that pressure and is 100% dry all the moisture has been converted into
The process of conduction between a solid surface and a moving liquid or gas is called convection. The motion of the fluid may be natural or forced. If a liquid or gas is heated, its mass per unit volume generally decreases. If the liquid or gas is in a gravitational field, the hotter, lighter fluid rises while the colder, heavier fluid sinks. For example, when water in a pan is heated from below on my stove, the liquid closest to the bottom expands and its density decreases. The hot water as a result rises to the top and some of the cooler fluid descends toward the bottom, thus setting up a circulatory motion. This is also why the heating of a room by a radiator depends less on radiation than on natural convection currents, the hot air rising upward along the wall and cooler air coming back to the radiator from the side of the bottom. Because of the tendencies of hot air to rise and of cool air to sink, radiators are positioned near the floor and air-conditioning outlets near the ceiling for maximum efficiency.
Radiate, by definition, means to send or spread out, and this is important to know when thinking about how exactly radiation occurs. We already discussed a child coming in from playing out in the snow, snuggling up to their father and getting warm through heat transfer by conduction- physical contact. Now, let’s say that the child comes inside from out in the cold, takes off their snow gear and places their hands over a hot fire instead. The child’s hands will warm up through the transfer of heat energy through radiation. Another example, which can be seen every day that you walk outside and the sun is shining bright- is the heat received on Earth by the sun, through the means of radiation. The Earth receives heat through the electromagnetic waves, and our bodies feel the warmth of the sun from these waves that are absorbed within our skin. Radiation is the only means by which heat energy can transfer through the empty space between Earth and the sun- neither conduction or convection have the ability to play a role in this area and therefore, we can see how truly important radiation is. Another interesting fact in regards to radiation is that “because more heat is radiated at higher temperatures, a temperature change is accompanied by a color change. For example, an electrical element on a stove glows from red to orange, while the
Thermodynamics is the branch of science concerned with the nature of heat and its conversion to any form of energy. In thermodynamics, both the thermodynamic system and its environment are considered. A thermodynamic system, in general, is defined by its volume, pressure, temperature, and chemical make-up. In general, the environment will contain heat sources with unlimited heat capacity allowing it to give and receive heat without changing its temperature. Whenever the conditions change, the thermodynamic system will respond by changing its state; the temperature, volume, pressure, or chemical make-up will adjust accordingly in order to reach its original state of equilibrium. There are three laws of thermodynamics in which the changing system can follow in order to return to equilibrium.