Name: heat transfer calculations with conduction, convection
Uploaded: 2023-09-18T17:11:17.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

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NC K-12 Science Standard Course of Study

9-12

Physical Science

Energy

PS.PSc.7.1

conduction-convection-and-radiation-problem-solving

Conduction, Convection and Radiation: Problem Solving

100m2 alana ve 1,5 W/mK ısı iletkenliğine sahip 13 cm kalınlığında bir duvar, bir odayı 3 santigrat derece olan dış atmosferden ayırır.
Duvarın dış yüzeyi 10 santigrat derecedir ve emisyonu 0.8'dir. Konvektif ısı transfer katsayısı 15 W/m2K ise, çevreye olan toplam ısı kaybı oranını bulunuz. Ayrıca, duvarın iç yüzeyinin sıcaklığını hesaplayın.
Burada, ısı transferinin üç mekanizması da söz konusudur. Isı, iletim yoluyla duvarın iç yüzeyinden dış yüzeyine aktarılırken, konveksiyon ve radyasyon nedeniyle çevreye ısı kaybı meydana gelir.
Konveksiyon yoluyla ısı kaybı oranı, sıcaklık gradyanına, yüzey alanına ve ısı transfer katsayısına bağlıdır.
Bu nedenle, konveksiyon ve radyasyon nedeniyle çevreye toplam ısı kaybı 13.27 x 103 W olarak hesaplanabilir.
Enerjinin korunumunu kullanarak ve ısı denklemindeki terimleri ikame ederek, duvarın iç yüzeyinin sıcaklığı hesaplanabilir.

<ol>
	<li>Stax'ı açın. (2019). Üniversite Fiziği Cilt 2. [Web sürümü]. <a href="https://openstax.org/books/university-physics-volume-2/pages/1-6-mechanisms-of-heat-transfer" adresinden alındı>https://openstax.org/books/university-physics-volume-2/pages/1-6-mechanisms-of-heat-transfer</a></li>
</ol>

İletim, taşınım ve radyasyon: problem Çözme

Isı transferi üç yöntemle gerçekleşebilir: iletme, taşınma ve radyasyon. Her yöntemin benzersiz ve ilginç özellikleri vardır, ancak üçünün de ortak iki özelliği vardır: sadece sıcaklık farkı nedeniyle ısı transferi yaparlar ve sıcaklık farkı ne kadar büyükse, ısı transferi o kadar hızlı olur.

Isı transferi ile ilgili bir problemi çözmek için ilk olarak durum incelenerek hangi ısı transferi yöntemi olduğu belirlenmelidir. Bu iletme, taşınma, radyasyon veya üçünün birleşimi olabilir. İkinci adım, problemden bilinmeyen miktarları belirlemek ve yazmaktır. Problemden verilenler veya çıkarılabilenlerin bir listesi yapılabilir, yani bilinen miktarlar, ardından belirlenen miktar için uygun denklemi çözmek.

İletim yoluyla ısı transferi için aşağıdaki denklem kullanılmalıdır.

<img alt="Equation1" src="/files/ftp_upload/14166/14166_Equation_1.svg" style="text-align: center; height: 46px;" />

Taşınma için ısı kaybı hızı sıcaklık gradientine, yüzey alanına ve ısı transfer katsayısına bağlıdır.

<img alt="Equation2" src="/files/ftp_upload/14166/14166_Equation_2.svg" style="text-align: center; height: 18px;" />

Aşağıdaki denklem radyasyon için net ısı transfer hızını verir.

<img alt="Equation3" src="/files/ftp_upload/14166/14166_Equation_3.svg" style="text-align: center; height: 25px;" />

Bilinen miktarları ve birimleriyle birlikte uygun denklemi kullanarak sayısal olarak çözerek doğru çözüm elde edilir.

İletim, Taşınım ve Radyasyon: Problem Çözme

Isı transferinin gerçekleşebileceği üç yöntem vardır: iletim, konveksiyon ve radyasyon. Her yöntemin benzersiz ve ilginç ...

Education

JoVE Core

Physics

Fizik

Unit 1

Ünite 1

Temperature and Heat

Sıcaklık ve Isı

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

heat transfer calculations with conduction, convection

Heat transfer calculations with conduction and convection use the temperature difference to find the rate of heat flow. Radiation can also be part of the process. The main idea is that heat moves only because one area is hotter than another, and a larger temperature difference leads to faster transfer.

To solve a heat transfer problem, first identify the type of transfer involved. It may be conduction, convection, radiation, or a combination of all three. Next, write down the unknown quantities and sort the given information from the problem statement.

After the known values are listed, choose the correct equation for the type of heat transfer. Use the conduction equation for heat flow through materials. For convection, the rate of heat loss depends on the temperature gradient, the surface area, and the heat transfer coefficient. For radiation, use the equation for net heat transfer rate.

Finally, substitute the known quantities and their units into the selected equation. Solve the equation numerically to find the answer. This method helps students work through heat transfer problems in a clear, step-by-step way.

Heat Transfer Calculations with Conduction, Convection

heat-transfer-calculations-with-conduction-convection

temperature and thermal equilibrium

Heat, Temperature, and Everyday Energy

Heat and temperature are key ideas in thermodynamics and in everyday life. People often connect temperature with hot and cold, but science gives it a more precise meaning. Temperature is the quantity measured with a thermometer. It is also linked to the average translational kinetic energy of particles. Heat is different from temperature. Heat is energy that moves from one place or material to another because there is a difference in temperature. That difference in temperature keeps heat...

zeroth law of thermodynamics

Thermal Equilibrium and the Zeroth Law

The zeroth law of thermodynamics explains thermal equilibrium between objects. If object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is also in equilibrium with object C. This transitive relationship is the key idea behind the law. A simple example uses metal blocks and a metal plate at room temperature. A cold metal block and a hot metal block are both placed on the plate. Over time, the cold block and the plate reach thermal equilibrium, and...

thermometers and temperature scales

How Thermometers Measure Heat

Thermometers measure temperature by using physical properties that change in a predictable way. One common example is volume. For most substances, volume increases as temperature rises. That idea is used in alcohol thermometers and in the original mercury thermometers. Other thermometer designs use different temperature-sensitive properties. Some measure electrical resistance, color, or the emission of infrared radiation. The alcohol thermometer is a common example. It contains red-dyed...

gas thermometers and the kelvin scale

Kelvin Temperature and Gas Thermometer Standards

Kelvin temperature is the absolute scale used in science, and it starts at absolute zero. That zero point matches the lowest possible temperature, where molecular motion reaches zero or the minimum allowed by quantum mechanics. Scientists use this scale because some physical quantities, such as the volume of an ideal gas, depend directly on absolute temperature. The Kelvin scale is part of the SI system of units, so its definition is more precise than simply using water’s freezing and boiling...

thermal expansion

Thermal Expansion in Air, Water, and Solids

Thermal expansion is the change in size or volume of a material as its temperature changes. A common example is the alcohol inside a thermometer. As the temperature rises, the alcohol expands and shows the change. Heated air also expands. It becomes less dense than the cooler air around it, so the surrounding air pushes it upward. This is why steam and smoke rise and why hot air balloons float. The same effect happens in liquids and gases, and it helps move heat upward in homes, oceans, and...

thermal stress

How Temperature Changes Create Stress

Thermal stress is the stress that builds up when an object changes temperature but cannot expand or contract freely. If the object would expand without restraint, the stress is compressive. If it would contract, the stress is tensile. This stress from heating or cooling can become large enough to cause damage. Engineers often reduce it by designing parts so they can move as temperature changes. Highway blocks, for example, are separated by gaps so thermal stress does not build up. When gaps...

thermal expansion and thermal stress: problem solving

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Thermal expansion and thermal stress are shown through the Golden Gate Bridge. The bridge faces temperatures from -15 °C to 40 °C. At its coldest, the main span is 1275 m long. Assuming the bridge is made entirely of steel, the example asks for the change in its length across this temperature range. To solve the problem, the known values must be identified first. The initial length is 1275 m. The coefficient of linear expansion for steel is 12 x 10 -6 /°C, and the change in temperature is 55...

heat flow and specific heat

Heat Units and Specific Heat

Heat is energy transferred because of a temperature difference, and it can change an object’s temperature. Since heat is energy, its SI unit is the joule (J). Heat transfer is the movement of energy from one place or material to another, and it plays a role in home heating, cooking, and many industrial processes. Two common units for heat are the calorie and the kilocalorie. A calorie (cal) is the energy needed to change the temperature of 1 g of water by 1 °C, specifically between 14.5 °C and...

phase changes

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Heat and phase change energy explain why substances melt, freeze, boil, and condense. A solid turns into a liquid during melting, also called fusion. The reverse process is freezing. A liquid turns into a gas during evaporation. The reverse process is condensation. Each substance changes phase at specific temperatures. The melting point is the temperature where a substance melts or freezes. The boiling point is the temperature where a substance boils or condenses. These temperatures depend on...

calorimetry

Heat Exchange in an Insulated System

Calorimetry studies heat exchange in an insulated system. A calorimeter is a container that prevents heat transfer in or out. Scientists use calorimetry to measure heat and specific heat capacity. A calorimetry problem is any situation where the objects are thermally isolated from their surroundings. The key idea comes from conservation of energy. During heat transfer, the heat gained by the colder object must equal the heat lost by the hotter object. A simple example is water poured into a...

mechanisms of heat transfer i

Three Ways Heat Moves Between Objects

Heat transfer happens when there is a temperature difference. It can move fast, like through a cooking pan, or slowly, like through the walls of a picnic ice box. Heat transfer appears in many everyday situations, so it is hard to find a place where it does not occur. There are only three ways heat is transferred: conduction, convection, and radiation. A fireplace shows all three at once. Radiation carries most of the heat into the room. Conduction also moves heat into the room, but much more...

mechanisms of heat transfer ii

Convection and Radiation in Heat Transfer

Convection and radiation are two major ways heat moves. In convection, thermal energy is carried by the large-scale flow of matter. Warm air and water rise because they are less dense, so ocean currents and large-scale atmospheric circulation move heat from the tropics toward the poles and move cold air from the poles toward the tropics. Earth’s rotation changes these moving air currents. It interacts with the flow and helps produce the eastward movement of air in the temperate zones.

conduction, convection and radiation: problem solving

Heat transfer calculations with conduction and convection use the temperature difference to find the rate of heat flow. Radiation can also be part of the process. The main idea is that heat moves only because one area is hotter than another, and a larger temperature difference leads to faster transfer. To solve a heat transfer problem, first identify the type of transfer involved. It may be conduction, convection, radiation, or a combination of all three. Next, write down the unknown...

radiation: applications

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Earth’s energy balance and the greenhouse effect help explain its average temperature. Earth is in radiative contact with both the Sun and dark space. It receives almost all of its energy from solar radiation, and it reflects some of that energy back into outer space. Dark space is very cold, about 3 K, so Earth also radiates energy into it. Heat can move quickly from soil and grasses, and frost can form on clear summer evenings, even in warm latitudes. In a first approximation, Earth’s...

absorption of radiation

Radiation Heat Transfer and Thermographs

Radiation heat transfer depends on temperature, surface area, and emissivity. The Stefan-Boltzmann law describes the rate of heat transfer by emitted radiation. In this law, σ is the Stefan-Boltzmann constant, A is the object’s surface area, and T is its temperature in kelvins. The fourth-power dependence on absolute temperature makes radiation highly sensitive to small temperature changes. Even a slight rise in temperature can change the emitted heat a lot. That sensitivity is why radiation...

key terms and concepts

Learn how to solve heat transfer problems by identifying conduction, convection, or radiation, choosing the right equation, and calculating the unknowns.

Heat Transfer Calculations with Conduction, Convection | JoVE K12

physics

JoVE Temel Fizik, kinematik, dinamik, akışkanlar mekaniği, statik, dalgalar ve akustik dahil olmak üzere temel fizik konularının teorisini ve uygulamasını kısa ve anlaşılması kolay animasyonlu videolarla tanıtıyor. Ek olarak, sektör içindeki bilim insanı videoları, dünya çapındaki günümüz laboratuvarlarında gerçekleştirilen klasik ve orijinal araştırma deneylerinde ilgili kavramların uygulanmasını göstermektedir.

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Chemistry

HS-PS3-3

HS-PS3-4

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Ohio’s Learning Standards and Model Curriculum

Energy And Waves

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Transfer and transformation of energy (including work)

Thermal energy

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PHYS.PS3.1

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112.49.c.8.

112.49.c.8.A.

Arizona Science Standards

Earth and Space Science

HS+E.E1

HS+E.E1U1.1

HS+Phy.P4

HS+Phy.P4U2.7

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Florida Department of Education

SC.912.P.10

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Energy Basics

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Mechanisms of Heat Transfer I

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Mechanisms of Heat Transfer II

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Conservation of Mechanical Energy

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Conservative Forces

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Non-conservative Forces

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Conservation of Energy

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Conservation of Energy: Application

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Use mathematics and computational thinking to explain the Law of Conservation of Energy in a mechanical system in terms of kinetic and potential energy.

PS.PSc.7.2

Work

Work is done when energy is transferred from one object to another. In other words, work is when a force acts on something that undergoes a displacement ...

Positive, Negative, and Zero Work

Work is done on an object when energy is transferred to the object. In other words, work is done when a force acts on a body that undergoes a displacement ...

Work-energy Theorem

According to Newton&#x2019;s second law of motion, the sum of all the forces acting on a particle (net force) determines the rate of change in the ...

Work and Energy for Variable Forces

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Work-Energy Theorem for Motion Along a Curve

The work-energy theorem can be generalized to the motion of a particle along any curved path. The simple argument here is that the curved path can be ...

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Work Done Over an Inclined Plane

The center-of-mass framework helps to easily describe the work done on rigid bodies. Since the internal forces in a rigid body do no work, they can be ...

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Work Done by Many Forces

The total work done on an object acted upon by multiple forces can be computed using two methods that give the same result. In one method, the work done ...

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Work Done by Gravity

Gravitation is one of the four fundamental forces in nature. The force between objects on Earth and Earth itself is called gravity.
Like other forces, ...

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Use mathematics and computational thinking to explain work in terms of the relationship among the applied force to an object, the resulting displacement of the object, and the energy transferred to an object.

PS.PSc.7.3

Power

The concept of work involves force and displacement; meanwhile, the work-energy theorem relates the net work done on a body to the difference in its ...

Power Expended by a Constant Force

The relationship between work done and the time taken to do it can be explained using the concept of power. For example, several sprinters in a race may ...

Construct an explanation to infer the relationship between work and power, both quantitatively and qualitatively.

PS.PSc.7.4

Analyze energy transfers and transformations within a mechanical system.

Heat Transfer Calculations with Conduction, Convection

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