Global warming and the growing demand for energy are two primary problems rising in the power generation industry. A simple solution to these problems has been researched for a number of years. The SCO2 Brayton cycle is often looked into as an alternative working fluid for power generation cycles due to its compactness, high efficiency and small environmental footprint. The usage of SCO2 in nuclear reactors has been studied since the early 2000s in development of Generation IV nuclear reactors, but the idea itself can be traced back to the 1940s. During this time however, no one really looked into the potential of supercritical CO2 since steam was found to be efficient enough, not to mention it was the more understood technology when compared to SCO2. In modern times though, demand of more efficient energy continues to rise and with it, the need for SCO2.
The potential of supercritical CO2 implementation is vast across power generation applications spanning nuclear, geothermal and even fossil fuel. The cycle envisioned is a non-condensing closed loop Brayton cycle with heat addition and rejection inside the expander to indirectly heat up the carbon dioxide working fluid. Read More
Because the most vital part of a refrigeration and HVAC system is to function optimally, compressors are used to raise the temperature and pressure of the low superheated gas to move fluid into the condenser. Consequently, refrigeration compressors must be properly maintained through regular maintenance, testing and inspection. There are a couple conditions which would indicate compressor problem or failures. However, with the right supervision it is possible to avoid further damage. Through this post we will identify and discuss some of these conditions: Read More
Variable Frequency Drive is found to be very effective in assisting with energy management for HVAC systems. The main objective of this technology is to ensure that the motor only generates enough energy to power the compressor and no more. VFD provides constant load-matching capacity which results in the elimination of over-capacity running. Recently studied, current variable frequency drive benefits goes beyond the advantage of energy savings or energy efficiency. In conventional common application, the installation of variable frequency drive saves about 35% to 50% energy used by matching system capacity to the actual load.
Freon (brand name by DuPont) used to be the regulated and most used refrigerant in the HVAC market. The chemical (R-22) was introduced to the refrigerant system in 1920. It consisted of hydrogen, carbon, fluorine and chlorine. HCFC was used in replacement to CFC or chloro-fluoro-carbon which is considered more dangerous. Within a few years, HCFC took over CFC’s role as the safer option.
Even though it was found to be safer than the alternative at the time, various recent studies state that R-22 is detrimental to the environment as it is a substantial ozone depleting substance that leads to greenhouse effects. Since January 2015, the maintenance or servicing of existing refrigeration, air condition and heat pump equipment using R22 has been prohibited by the EPA (Environmental Protection Agency) and related international agencies. Based on the Montreal Protocol, which prevents more damage to the ozone layer by banning all ozone deteriorating substances, R22 can no longer be used in any kind of application.
In its natural state, heat flows from higher to lower temperature regions. Refrigeration cycles are utilized to modify or reverse this cycle, using work obliging heat to flow with the direction that is desired, and align with increasing temperature from low temperature region to higher.
During the earliest records of the “cooling” process being invented, people harvested ice to refrigerate, cool and conserve food. As time progressed, humanity’s basic needs changed and new ways to manipulate temperature started being explored. Major research into refrigeration began with the creation of pup to create a partial vacuum container which absorbs heat from the air. That being said, while the experiment was successful it did not have any practical applications.
The majority of HVAC installations dating back to the 1990s have R-22 as their main working fluid. However, recent studies have proven that R-22 or as we commonly known as “Freon” (brand type) is not as environmentally friendly as we once thought it was. Ergo the use of this refrigeration type has been banned by the Environmental Protection Agency along with other substances which contributes to ozone depletion. With phasing out of R-22, HVAC manufacturers and end-users are forced to look into other comparable refrigerants which won’t negatively impact the environment as much.
R-410A offers a few benefits when compared to the traditional R-22 fluid – one of which is greater energy efficiency which translates into lower operational costs. This hydro-fluorocarbon has been approved for use in new systems and is classified as a non-ozone-depleting HFC. One note that has to be taken into consideration is that R-410A operates on roughly a 50% higher pressure than R-22, thus can only work with high pressure limit equipment.
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.
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.
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.