Heat Transfer in Structures
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Provide an example and explain in detail how each mode of heat transfer would move through a structure and compromise life safety and cause fire damage to the structure.
Conduction is the movement of heat between different solid molecules. Heat travels in solid materials differently. Some materials such as steel and copper conduct more heat than others including fiber grass, which is a bit rigid and inefficient in passing heat. Poor heat conductors prevent heat from reaching the building (Rabady, 2010). Good conductors pose a risk as they may quickly conduct heat and even fire, and if not well checked, they may cause damage.
Convection is defined as heat movement in fluids. The heat released by the liquid results in warm air while the dense cold air flows downward, and the circulation results in conventional currents. The movement of heat in fluids is dependent on the volume of air in the atmosphere, the temperature of the heated molecules, and the philosophy and speed of air movements. In case the molecules move at a very high speed, they may pose a challenge to structures, especially in the case of a fire. Cool air descent reduces the effort of putting out the fire, and at times firefighters might be forced to use their mechanisms to put off the fire.
The transfer of heat in space is commonly referred to as radiation. This mode of heat transfer differs from convection and conduction since heat does not travel through space, and air does not influence heat transfer instead of light energy. Common heat transfer mechanisms by radiation include sun and campfire energy. The structure that is the recipient of radiant energy warms up and absorbs the energy. The designs may pose a danger only if they cannot combat too much of the radiant heat significantly depending on the angle at which they receive the energy, their optical properties, and the distance between the bright heat source.
Explain in detail how the heat would affect the life safety of the occupants in a building fire and what steps occupants should take to lessen the effects of each type of heat transfer through a building.
Occupants of a building should be aware of safety measures put in place in case of a fire. The owner of the structures should also factor in the safety measures during construction to maintain the occupants’ safety (Yoshida et al., 1969). Building occupants should minimize the use of fuel sources to reduce the chances of fire. Any ignition present should be communicated to the occupants so that they are aware. Any fire systems or extinguishers should be well placed to ensure they are on the radar. Fire containment is important because spreading to large areas may cause significant havoc to the structures. Timely extinguishing using the appropriate materials is vital to minimize damage.
How does the design and layout of a structure affect heat transfer and the life safety of the occupants and firefighters who will be combating the fire. Some structures are faced with threats, including lighting, primarily when they conduct electric currents and lack protective mechanisms such as lighting arrestors. Tall buildings are also at risk, and caution should be exercised, especially where electricity is in place. People should construct Factories, laboratories, and kitchens to reduce risks to the occupants, especially where heat is involved. Any installation put in place should be checked and authorized, and owners should regularly conduct maintenance. Occupants of the building should escape in case of a fire emergency through appropriate exit routes.
Also, explain in detail what aspects of the three types of heat transfer that you will need to be aware of when combating a fire. That is, explain the actions that firefighters may take that would lessen or worsen the effects of heat transfer in a structure fire. There are things that fire-fighters may do that worsen or lessen the effects of heat transfer. Therefore, feel free to discuss at length any actions you think you would take or things you would do to restrict and lessen heat transfer through a structure.
Fire protection mechanisms on structures put in place are based on two factors: Occupants exit from buildings and duration of putting out the fire. Various strategies include a separating wall, compartment wall, and external wall that prevent fire from spreading to adjacent structures (Indo-Swiss Building Energy Efficiency Project (BEEP, 2019). Passive compartmentation is also essential in ensuring that rapid spread of fire is minimized, fire from growing and transferring the danger to the occupants, and reduces the damage caused in the buildings.
References
Indo-Swiss Building Energy Efficiency Project (BEEP. (2019). Heat Transfer in buildings Part 1: BEEP Camp 2018. In YouTube. https://www.youtube.com/watch?v=c4lIXVUu18I
Mechanical Concepts. (2017). Modes of Heat Transfer and its mechanism | Conduction-Convection-Radiation | HT-1. In YouTube. https://www.youtube.com/watch?v=QyjU-noH9rg
Rabady, R. I. (2010). Modes of Heat Transfer in the Leidenfrost Effect. Heat Transfer Research, 41(2), 129–135. https://doi.org/10.1615/heattransres.v41.i2.20
Yoshida, K., Kunii, D., & Levenspiel, O. (1969). Heat transfer mechanisms between the wall surface and fluidized bed. International Journal of Heat and Mass Transfer, 12(5), 529–536. https://doi.org/10.1016/0017-9310(69)90036-2Response to Nick
I agree with you that when a person touches a hot stove they get burnt and therefore this is a conduction means of heat transfer. The mixing of dense and less dense air also results in the creation of convectional currents and therefore the convectional method of heat transfer. It is also true that thorium and uranium are radioactive gases used in NFPA 90A. The measures of preventing the fire from destroying houses and the property are also true and they have a great positive impact on the residents. The house structure has a great impact on the level of the burning of the house and heat transfer. Knowledge of the three ways of heat transfer is necessary when dealing with heat.
Response to Malcolm
I agree with you that radiation, convection, and conduction are methods of heat transfer and they have a great impact on the extent to which fire burns and heat goes within a structure. I agree with you that an open floor plan will burn in a less manner compared to a flashover. The best way to control fire in a house is indeed by controlling the openings which include windows and doors.
