Aerodynamic Force Sources: Pressure & Shear Stress

The next time you hear an airplane flying overhead, look up, and pause for a moment. What you see is a machine that is heavier than air, but which is somehow being sustained in the air. This is due to the airflow over the airplane. This airflow exerts a lift force which counteracts the weight of the airplane and sustains it in the air—a good thing. The airflow also exerts a aerodynamic drag force on the airplane which retards its motion—a bad thing. The drag must be counteracted by the thrust of the engine in order to keep the airplane going. The production of thrust by the engine consumes energy. Hence, the energy efficiency of the airplane is intimately related to aerodynamic drag. This is just one of many examples where the disciplines of aerodynamics and energy interact. (more…)

Types of Engineering Materials Available for Microtechnology-Based Energy and Chemical Systems

Engineering Materials
Silicon is the material of choice for most Micro Electro Mechanical Systems due to (1) the feature size often being in the range of less than 20 mm requiring single crystalline material and (2) the dependence on fabrication techniques developed by the electronics industry for processing this material. However, it is a particularly poor choice for the larger thermally based devices that characterize Microtechnology-Based Energy and Chemical Systems. The room temperature thermal conductivity of silicon is approximately 150 (W/mK). Use of this material leads to high rates of heat transmission across the short distances where temperature gradients occur. The thermal conductivity of silicon above 10001C falls to below 25 W/mK, but the average value can still be high. (more…)

Heat Exchangers, Evaporators, and Condensers | Energy Application of Micro Technology

The most fundamental process from an energy systems standpoint is heat transfer to (or from) a working fluid. This unit operation typically occurs in small channels, the characteristic diameter of which is less than 1 mm. Other heat transfer exchanger configurations, such as fluid flowing through a network of posts or through a mesh, are also possible. Specific examples of this fundamental unit operation include phase change occurring in boilers (modular steam boiler), evaporators, and condensers. (more…)

Miniature and Microscale Heat Engines for Power Generation Propulsion

Many characteristics of traditional engines make them attractive for use in power generation and propulsion technology. They tend to be self-aspirating and rely on combustion, which at the macroscale is a very robust form of heat generation. Fuel is plentiful and inexpensive, with storage easily realized. The energy density of the fuel (or fuel plus container), when compared with electrochemical sources, is high. Along with these advantages come a number of drawbacks, especially where miniaturization is concerned. For example, an engine is thermodynamically restricted (by the Carnot efficiency) in its conversion of chemical energy to work due to the intermediate heat-generating step. (more…)

Limitations of Hot Water Steam Heating

hot water steam heating
Steam is a great heat transfer medium simply because it’s easy to move inside your system. Steam heating is known to have a very high heat retention capacity. The heat capacity of steam is much bigger compare than that of water. Steam systems are frequently working on very low pressure and generally below 220F. (more…)

Fuel Cell Engine Auxiliaries: Fuel Cell Vehicle Systems

Numerous other parts are needed for a complete fuel cell engine suitable for motor vehicles. These auxiliary components include many familiar pieces of equipment, such as blowers, pumps, heat exchangers, sensors, and controls. However, fuel cells have specialized performance requirements, so substantial engineering effort is needed to develop auxiliary systems suitable for fuel cell vehicles. (more…)

Heat Recovery Ventilators Radiation & Convection Recuperators

heat recovery recuperators
In these regenerators the heat energy transfer between primary and secondary fluid is primarily by radiation and its installation is always done in a vertical stack.This type of exchange is strongly favoured by temperature, so that these retrievers are especially suitable in the following cases: (more…)

Hot Water Steam Heating Advantages

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Steam heating is an absolutely wonderful method to heat your home. Steam heat is always driven by steam produced from water in a pot of natural gas, oil and electricity. Then it draws through pipes and radiators and heat exchangers to heat your house or residential. Boiler is used to generate steam from water. When the water boils, steam rises through pipes to radiators to heat. Then, the hot radiators play its role to warm the house. (more…)

Boiler Insulation System – Material and Jacket Selection

boiler insulation system
Insulation is what keeps the heat energy of a boiler system from leaking out of the system on its way to the end users. Inspect the condition of your insulation often enough to keep the insulation from becoming seriously deteriorated. This measure summarizes what insulation does, what to insulate, and how to insulate. It also gives you several methods of finding defective insulation, even if it is buried. (more…)

Cryocooling for Heat Transfer and Heat Exchanger

cryocooling heat exchanger

Micro technology can be employed to produce miniaturized refrigeration and cryocooling systems. Although process intensification is typically the route used for miniaturization, micro technology can also be used for reducing the size of mechanical components that are necessary for operation. For example, to create a small-scale vapor compression refrigerator, (more…)

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