Heat transfer

Thermodynamics is the branch of physics that studies thermal energy and is based on the so-called laws of thermodynamics that describe its properties and how energy is transferred and converted into other forms.

The laws of thermodynamics are as follows:

  • First Law of Thermodynamics (Principle of Conservation of Energy): The total energy of a physical system is constant, and the difference between the initial and final energy is equal to the amount of energy that is transferred or which becomes work.
  • Second Law of Thermodynamics (Principle of Entropy): In a thermodynamic transaction, the total amount of entropy of a system and its surroundings always increases or remains constant.
  • Third Law of Thermodynamics (Zero Entropy Principle): At absolute zero temperature, the entropy of a perfect pure system is zero.

Some of the main factors we have to keep in mind when we talk about thermodynamics are temperature, pressure, amount of substance and entropy.

In this section we talk about thermal equilibrium, temperature, the kinetic theory of gases, heat capacity, sensible heat, latent heat, phase changes, the heat capacity of a solid, the heat capacity of a gas, adiabatic systems, types of heat exchange, convection, conduction, radiation, psychrometric diagram, etc.

HRSG

by

HEAT RECOVERY STEAM GENERATOR HRSG and the importance of Economizers In a world increasingly aware of sustainability and energy efficiency, the need to recover and optimize available resources in industrial processes is crucial. One of the key elements in this process is the HRSG (Heat Recovery Steam Generators), designed to capture residual energy and convert it into steam. While the manufacture of HRSG is not part of your company’s offering, the economizers and heat exchangers you provide are essential components for improving the efficiency of these systems. What is an HRSG and how does it relate to economizers? HRSGs are equipment designed to recover thermal energy from exhaust gases in industrial processes or power plants. This residual energy is converted into steam, which can be used for power generation or industrial heat processes. While HRSGs are critical for this type of recovery, economizers play a crucial role in improving the overall efficiency of this process. An economizer is a heat exchanger designed to capture residual heat from exhaust gases before they are released into the atmosphere. Its main function is to heat the feedwater before it enters the boiler or steam generation system, thereby reducing energy consumption and improving the overall system efficiency. Benefits of economizers in energy recovery  The economizers and other heat exchangers we offer have a direct impact on reducing energy consumption and emissions, two key factors in the sustainability of any industrial operation. Here are some of the most notable benefits: Improved energy efficiency: A well-designed economizer recovers heat from exhaust gases, increasing system efficiency without the need to invest in additional fuels or resources. This energy savings is essential for any industrial plant. Reduction in operational costs: By better utilizing residual energy, economizers help reduce costs associated with fuel use and other energy sources. This is especially relevant for companies operating in energy-intensive industries. Reduced pollutant emissions: By recovering more energy from exhaust gases, the need to burn additional fuels is minimized, helping reduce CO₂ emissions and other harmful gases. Durability and robustness: Our heat exchangers are designed to withstand extreme conditions, ensuring a long lifespan and minimal maintenance. This is crucial for industries that require continuous and reliable operation. How heat exchangers optimize HRSG efficiency Heat exchangers are essential for maximizing the efficiency of an HRSG system. These units can be integrated into the overall design of the plant to optimize heat transfer between exhaust gases and feedwater. These exchangers not only improve efficiency but also enable better management of exhaust gas temperature, ensuring valuable thermal resources are not wasted. Optimizing heat transfer in the process can be achieved through better material selection, design, and configuration of exchangers, which improves heat recovery and increases the overall performance of the HRSG. Our products: Tailored solutions for more efficiency energy Our company specializes in the manufacturing and supply of economizers and heat exchangers designed to maximize energy recovery in industrial systems and help companies achieve greater energy efficiency. Our products not only allow for better recovery of residual heat but also provide an economic and efficient solution for reducing operational costs and minimizing environmental impact. Energy efficiency is a priority for many industries, and the solutions we provide are designed to ensure more sustainable operations, reducing expenses and improving plant performance. With custom designs for each need, our solutions can be integrated into various types of industrial processes, from power plants to chemical and textile processes, improving both productivity and sustainability. Why choose our economizers and heat exchangers? Customization: Our designs can be adapted to the specific needs of each client, ensuring energy performance is optimized to the maximum. Improved efficiency: With our range of economizers and heat exchangers, we can help companies reduce costs and increase overall operational efficiency. Commitment to sustainability: We advocate for solutions that contribute to reducing environmental impact, helping companies comply with regulations and reduce emissions of harmful gases. Reliability and durability: Our products are built to last, even in the most demanding conditions. The integration of HRSG, economizers, and heat exchangers in industrial systems is essential for achieving greater energy efficiency, reducing costs, and contributing to sustainability. While HRSGs are vital in many processes, their effectiveness depends largely on auxiliary components like economizers and heat exchangers. Our company offers solutions designed to optimize these processes, improving efficiency and reducing operational costs. If you want to learn more about how we can help you improve your plant’s energy efficiency, feel free to contact us. We would be happy to help you find a tailored solution that meets your needs.

Types of heat exchangers

by

TYPES OF HEAT EXCHANGERS There are many types of heat exchangers and various ways to classify them. In this article, we will classify them based on: 1. Classification by Construction Direct contact Indirect contact Tube heat exchangers Plate heat exchangers 2. Classification by Operation Liquid-liquid heat exchangers Liquid-gas heat exchangers Gas-gas heat exchangers Bulk solid heat exchangers Classification by Construction Heat exchangers can transfer energy via direct contact, that is, by fully mixing the fluids, with cooling towers being one of their main examples. However, this system can lead to the transmission of contaminants between the two fluids, making it unsuitable for most cooling systems, energy recovery, and treatment of gases, liquids, and bulk solids. In these cases, where it is necessary to keep the two fluids separate, an indirect contact system is used. This construction involves an element, usually plates or tubes, which act as a wall and keep the two fluids separate. Within the category of indirect contact exchangers, there is a special case: rotary heat exchangers, where both fluids travel through the same space but alternately, which could cause a slight mixing, but this is considered almost negligible. Focusing on the two main families of indirect contact, those of plates and tubes, it can be said that for the same power, plates achieve a high heat transfer coefficient in a very compact space, but they reduce the fluid flow area, making them more prone to fouling. On the other hand, tubes provide a larger surface area for fluid flow, making them highly recommended in dirty, dusty environments, or with sticky, viscous fluids, or even with sediments. They are less likely to become clogged and thus also reduce maintenance and cleaning costs. Tube heat exchanger Tube heat exchangers consist of cylindrical, flat, or oval tubes, and their design is chosen based on the specific characteristics of each system. Within this family, we find: Smooth tube heat exchangers. Since they have a similar exchange surface both inside and outside the tubes, this is a very common design when working with fluids that have similar specific heat values. Thus, in applications between two air flows, we can refer to classic smooth tube exchangers, while in applications involving water, sludge, milk, or juices, we can refer to tubular, multitubular, pyrotubular, coaxial, or double-tube exchangers, as well as shell and tube exchangers. Tube and fin heat exchangers. These are specifically designed to compensate for the energy transfer between two fluids with different specific heat values. This is a common situation in systems where gas flows are in contact with other fluids such as superheated water, thermal oil, refrigerants (ammonia, R134, R410a, etc.), or steam. For example, the specific heat of gas is around 1,214 kJ/m³·K, while the specific heat of water is 4,186 kJ/m³·K. This means that water can release almost four times more heat than the air can absorb, and the way to correct this is by increasing the exchange surface on the air side using elements called fins, which can be continuous plates perpendicular to the tubes or helical plates wrapped around the tubes. Plate heat exchanger Plate heat exchangers consist of flat or corrugated plates. Among them, we find different designs suited to various applications: Pillow plate heat exchanger. Emerging technology, very versatile and efficient, with a surface in the shape of a pillow, giving it the name “pillow.” Its design allows it to handle not only viscous, sticky, and sediment-laden fluids, but also to transfer energy to granular solids. This makes it an excellent alternative to fluidized beds, reducing energy consumption, minimizing waste, lowering environmental pollution, and improving the final product quality by applying energy uniformly. Cross-flow plate heat exchanger. A plate system widely used in energy recovery for applications such as air conditioning, directly integrated into air handling units. It is an excellent system for achieving high efficiency, but it requires advanced air filters, as its compact form makes cleaning difficult. Welded plate heat exchanger. The plates are joined by welding, which prevents internal cleaning and limits their use to installations free from contamination. Plate and gasket heat exchanger. The gasket system allows plates to be disassembled, cleaned, and replaced. This makes it more versatile than the welded system, but the channels through which the fluids pass remain small and can easily become blocked, making them unsuitable for viscous, sticky, or sediment-laden fluids. Classification by Operation Heat exchangers are designed to transfer energy optimally. To maximize their efficiency, it is essential to consider the type of fluids and their properties. An example of this is the previous case, where heat exchange occurs between a gas with a specific heat of 1,214 kJ/m³·K and water with a specific heat of 4,186 kJ/m³·K. Similarly, we find: Liquid-liquid heat exchangers. These include pillow plates, welded plates, plate and gasket exchangers, concentric tubes, coaxial tubes, and pyrotubular exchangers. Liquid-gas heat exchangers. These include smooth tubes, tubes with continuous fins, and tubes with helical fins. Gas-gas heat exchangers. These include multitubular exchangers, smooth tubes, and cross-flow exchangers. Bulk solid heat exchangers. These use the Pillow Plate technology. Small design details can increase or decrease turbulence, enhancing the exchange coefficients and leading to substantial differences between one supplier and another. That is why investment in R&D is a key factor in the evolution of this sector, which is increasingly recognized for its contribution in terms of efficiency, savings, and sustainability.

Conduction, convection & radiation

by

CONDUCTION, CONVECTION & RADIATION HEAT TRANSFER IN NATURE In nature, we find fascinating examples of heat transfer through conduction, convection, and radiation—three fundamental mechanisms in thermodynamics. For example, imagine a summer morning at the beach. Early in the morning, the air remains calm because there is a thermal equilibrium between the temperature of the air mass over the sea and the air mass over the land. As the Sun heats the Earth’s surface, the temperature of the air over the land rises more quickly than that of the air over the sea. This creates a thermal contrast: the warm air over the land rises, while the cooler air from the sea moves toward the land to take its place. This movement of air masses is a clear example of thermal convection, the same principle that allows hot air balloons to rise. The more the Sun heats the land, the stronger this temperature difference becomes, increasing the speed of the sea breeze. This rising warm air favors the formation of small cumulus clouds, and if the temperature difference is significant enough, cumulonimbus clouds may appear, which are responsible for sudden summer storms. Unlike radiation, which transfers energy without direct contact (such as the Sun’s rays heating the sand), convection depends on the movement of fluids like air or water. On the other hand, thermal conduction occurs when two objects at different temperatures come into contact—for example, when we walk barefoot on hot sand at noon and feel the heat transferring to our feet. So, the next time you’re at the beach and notice the sea breeze picking up at midday, think of BOIXAC, the specialists in thermal exchange for the industry.

Quality matters to us, so does your privacy
Boixac Tech SL, on its website https://boixac.com/en/, uses cookies and other similar technologies that store and retrieve information when you browse. These technologies may serve various purposes, such as recognising users and obtaining information about the user’s browsing habits. The specific uses we make of these technologies are described in the Cookies Policy. On this website, we have our own and third-party cookies for accessing and registering users' forms. Information about cookies can be found on the MORE INFORMATION button in the Cookies Policy. In accordance with the use of cookies approved in July 2023, with the criteria of the European Committee on Data Protection, (CEPD), by the RGPD-UE-2016/679, LSSI-CE-2002/21/CE, update, 09/05/2023, we request your consent for the use of cookies on our website/App. Click here to read our Cookies Policy.
More information Deny Accept
Quality matters to us, so does your privacy
Choose which cookies you accept. In the case of rejecting them, Boixac Tech SL cannot guarantee the full functionality of the page. Your choice will be kept for one year. Click here to read our Cookies Policy.
Save Deny Accept