A few decades ago, opening and closing a window was enough air temperature control. In modern days though, the standard bar of comfortable living has become higher and the occurrence of global warming, which raises the world’s temperature to the extremes, is abundant. With all this in mind, temperature control becomes a major necessities. During this post, we will be exploring factors which should be considered for a new installation of a HVAC system either to modern or conventional homes.
Regardless of the size of property, ductwork that is balanced and well designed must be installed to make sure that the air and temperature circulation is optimal –especially for locations with extreme weather conditions. Externally insulated round ducts are found to be the most efficient. Installation of balance dampers in the ductworks should also be important to regulate airflow.
Familiar to many, the 2011 SuperTruck program was a five-year challenge set by the U.S. Department of Energy to create a Class-8 truck that improves fuel efficiency by 50 percent. Hoping for even more groundbreaking achievements this time around, the Department of Energy has initiated a second five-year program to bring further fuel-efficiency advancements and near closer to eventual commercialization. Cummins, Peterbilt, Daimler Trucks North America, Navistar, and Volvo Group remain the five teams involved in this R&D endeavor. Michael Berube, head of the Energy Department’s vehicle technology office mentioned “SuperTruck II has set goals beyond where the companies think they can be.” SuperTruck II is looking for a 100 percent increase in freight-hauling efficiency and a new engine efficiency standard of 55 percent. With such lofty goals, the SuperTruck II development teams will need to tackle improvements in freight efficiencies from all sides.
Material considerations, body aerodynamics, low-resistance tires, predictive torque management using GPS and terrain information, combustion efficiency, and several other improvements methods on the first iteration have demonstrated how the SuperTruck II will require a multi-phase and integrated systems approach to achieve equally successful numbers. However, with an engine efficiency target that is 31 percent above the SuperTruck’s first go around, special attention will be required on engine advancement to achieve an efficiency standard of 55 percent.
A compressor unit is an important component in an air conditioning system used to remove the heat laden vapor refrigerant from the evaporator. The compressor raises the temperature and pressure of the working refrigerant fluid and transforms it to a high temperature and high pressure gas. Since the compressor is one of the most vital parts of a cooling system, to be able to have an efficient working cycle, an appropriate and optimum compressor design must be installed.
Generally, there are 5 types of compressor that can be used in HVAC installations, the most common of which being reciprocating compressors used within a smaller scale conditioning system. Reciprocating compressors utilize pistons and cylinders to compress the refrigerant and an electric motor is used to provide a rotary motion.
During the last decade the development and extensive use of unmanned air vehicles (UAV) has accelerated the need for high performing micro gas turbines. In fact, their large energy density (Whr/kg) makes them attractive not only for UAV application, but also for portable power units, as well as for distributed power generation in applications where heat and power generation can be combined.
Micro gas turbines have the same basic operation principle as open cycle gas turbines (Brayton open cycle). In this cycle, the air is compressed by the compressor, going through the combustion chamber, where it receives energy from the fuel and thus raises in temperature. Leaving the combustion chamber, the high temperature working fluid is directed to the turbine, where it is expanded by supplying power to the compressor and for the electric generator or other equipment available .
Axial and mixed flow fans have been in high demand for a number of years. The application of these machines span many different industries including HVAC, automotive, appliance, military equipment, and much more. Like many other types of turbomachinery, changing industry standards and market trends have resulted in fierce rivalry to compete on lifespan, efficiency, environmental and user friendliness, and overall quality. With this in mind, it goes without saying that companies are looking for tools needed to develop highly efficient equipment while minimizing noise as quiet fans are typically more desirable which results in higher demand and marketability.
In the last post, we covered the area of HVAC dealing with air conditioning and refrigeration. For today’s blog post, we’d like to quickly go over the other major topic of HVAC industry – heating systems. In geographical areas where temperature fluctuation tends to be quite extreme, a good working heating system is a vital necessity –especially during the colder winter months. The main challenge of heating systems frequently comes from the heat distribution method. There are a couple types of heating system and it is important to take into account their functionality to decide which is the best type for your application.
The first systems we are going to focus on is central heating, which is the most common heating system in North American residential applications. This system comes with primary heating applications such as a furnace, boiler, and heat pumps. Each heat source is rather unique and uses different methods of distributing heat into the targeted environment. Furnaces use ducts to blow heated air through in order to disperse the generated energy. Implementation of such technology in the USA is controlled by the Annual Fuel Utilization Efficiency where it estimates seasonal efficiency, averaging peak and part-load situations. Boilers utilizes hot water which travels up to radiators and gets circulated around in a system – so instead of using a fan and ducts, appliances which utilizes boiler as a heat source commonly uses pump to flows the hot water to other parts of the house/building. Since circulation is the most recurring challenge in heating appliances, an optimal pump design must be installed into the system to make sure that the heat is distributed evenly to each part of site. Within central heating there is also heat pump system which works as two-way air conditioner (direct and reverse). During the hotter season, heat pumps work to moving heat from indoor (cooler) to outdoor (higher temperature), and vice versa during the colder months. Heat pumps generally use electricity to move heat from one place to another.
During the past week we’ve talked about challenges, improvements and development of HVAC technology. But taking a step back, what is a HVAC system? Heating, ventilation, air conditioning systems and refrigeration (or known as HVAC&R) is a technology developed to manipulate environment temperature and air quality. The applications of such technology are based on the principles of thermodynamics, fluid mechanics and heat transfer.
Commonly HVAC systems are grouped into four main systems starting with the heating and air conditioning split system, which is the most ordinary implementation of residential applications encompassing both inside and outside installations. The application, which can be controlled with a central thermostat, consists of air conditioning system which cools the refrigerant to drop the temperature, and heating system which involves gas furnaces. Ducts used to circulate the adjusted air from both heating and conditioning, with the help of evaporator/fan coils – a terminal unit which is used to provide heating or cooling to the targeted space.
Turbomachinery design has significantly evolved over the last two decades, as supporting education and training methods and techniques remains a challenge. Diversity of technologies covered in the varying courses and extensive use of software by industry designers makes the task of delivering the course curriculum that meets expectations of industry and students difficult. Many educational institutes and business use generic CAE tools for the purpose of learning turbomachinery through student projects. While generic tools have proven their value in research and design, the comprehensiveness of these tools to tackle real life turbomachinery situations is far from desired. The inexperience of fresh graduates from universities and colleges in their inability to perceive a 4D machine (3D plus time), traditionally taught using a 2D blackboard, is evident. A student is not only required to have a very good understanding of underlying fundamentals, but is also required to address multitude of design, analysis and optimization problems within the limited time available for education. Coupling of theoretical and computer aided design knowledge to augment the capability of students to contribute to the industrial endeavor is necessary. Such a solution provides students with implicit understanding of the level of detail required by final designs, such as mean line design to the specification of a blade profile varying from hub to tip of a blade, and further complexities of iteration due to an aerodynamically correct blade profile being unsuitable because of stress levels or excitation frequencies and much more. AxSTREAM® EDU introduces multiple dimensions of design required by turbomachinery very early in the instruction process which, by using, the students are able to develop insights that traditionally are difficult to attain in the same time frame. The use of AxSTREAM® EDU as a design software has been proven to multiply the skills of the students, enabling broad 3-D design considerations and visualization seldom possible otherwise.
While the term of air conditioning in relation to automotive might instantly correlate to a system which provides passenger with a comfortable air temperature/environment, HVAC systems also are used for heating and cooling of batteries in such application as well as cooling of the vehicle fuel systems. Thermal management for automotive application isn’t easy though. Many factors have to be accounted for in order to build a dependable cooling system.
While talking about HVAC concerns and challenges which arise in automotive application, the biggest inconvenience commonly comes down to the lack of cold air produces. Mobile refrigeration/air conditioning systems come with quite a few concerns from two sides: the refrigeration side, where it removes heat and injects cold air, and from the electrical side which provides control. From the system, the most common challenges are found in moisture –which would fail the cooling system if present in the air, soiled condenser which would block air flow, and various other mechanical complications which might occurs.
Humid climates commonly come with the challenge of moisture standards. When HVAC (heating, ventilations, and air-conditioning) systems do not maintain proper moisture conditions/humidity control, it causes damages and defects to the building.
A humid climate is defined as a condition where the average monthly latent load (energy required to remove moisture from the air) of environment’s air is the same or higher than the average monthly energy needed to cool the air during the cooling season. Using air with high latent load easily brings moisture in and accumulates it in building materials.
Maintaining humidity control isn’t an easy task. The HVAC unit has to be able to support a proper pressurization system using dehumidified air to entire the building. In order to provide the right dehumidification, a HVAC system must be able to dehumidify the air that flows across the cooling oil (which means the precise sizing of cooling coil must be selected to meet the load of both outside and return air). That is not the only criteria that an HVAC system needs to fulfill though. The system must also meet the sufficient run time to remove moisture from the interior air. In a humid condition, temperature control is not enough. Moisture control comes second on the priority list ( though this has to be fulfilled without scarifying the main goal of giving comfortable temperature to users).