Introduction
Because of energy want, all the countries in the world are studying and developing new kind of energy and the techniques of saving energy [1].Cooling is the largest single demand on electrical consumption in the world and the synthetic refrigerants that are utilized by most cooling appliances add significantly to climate change and ozone depletion [2]. Ozone depletion and global warming (or more accurately, climate change) are major environmental concerns with serious implications for the future development of the refrigeration based industries. The need to reduce the emission of greenhouse gases have not yet been fully appreciated [3]. The growing international concern towards relatively high global warming refrigerants has motivated the study of low global warming alternatives for HFC’s in a domestic refrigerator [4]. Halogenated refrigerants used in vapour compression refrigeration, air conditioning and heat pump systems cause greenhouse gas emissions which, in turn contribute significantly to the global warming. One effective solution to reduce this type of green house gas emission is using environmentally friendly and energy efficient refrigerants [5]. LPG is environmentally acceptable alternative substances and cheap in nature, their use as a refrigerant in domestic refrigerators is very attractive [6]. Although HC refrigerants have highly flammable characteristics (A3) according to the standards of ASHRAE as a negative specification, they have not only several preferable specifications such as zero ODP, very low global warming, non- toxicity and higher performance than other refrigerant types but also have high miscibility with mineral oil and good accordance with the existing refrigerating systems. They are us...
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...s (3m, 3.5m, 4m, 4.5m, and 5m) is used. A set of five number hand shut-off valves were fixed before the five capillary tubes to direct the flow from the drier to the required capillary type. The ends of the capillary tubes were connected by a distributed arrangement by brazing onto a common tube on leading the arrangement onto the evaporator. The temperatures at the salient points were measured by calibrated RTD (PT-100) sensors .The total energy consumption of the system as well as the compressor is measured by a digital energy meter .The estimation of the COP of the domestic refrigerator was done with the help of an insulated calorimeter setup consisting of a steel drum with exactly the same length of the evaporator used in a domestic refrigerator. The calorimeter is filled with brine solution as a secondary refrigerant. The experimental setup is shown in figure 1
In this paper over natural refrigerant I will be covering the pros and cons of natural refrigerant in light commercial and residential applications. There are many natural substances in this world that can be used to help or decrease the efficiency of a heating ventilation air conditioning system. Some of these substances are water, air, ammonia, and hydrocarbons. All these substances are natural that come from the earth we live on. Over the course of this paper I will be covering the pros and cons of swamp coolers, geo thermal heating and cooling units and how these natural substances can help and or decrease how your heating and cooling unit performs.
An Investigation Into How the Thickness of Insulation Affects the Time a Drink Takes to Cool Down
Transformer oil is organic and therefore oxidizes and decays; creating oxidation by-products which destroy the paper insulation. The aging of transformer oil is caused by the oxidation process of the oil; therefore, c...
The metering device of a refrigeration unit regulates the flow of refrigerant to the evaporator and divides the high from the low pressure side of the system. Capillary tube usually consists of a predetermined length of tubing having a small inside diameter. A thermostatic expansion valve meters the refrigerant based on different temperatures and pressure. The type that operates in response to the evaporator pressure is called an automatic expansion valve. The refrigerant lines carry the refrigerant liquid and vapor between the system components.
The membrane contactors can be used in different components of the absorption refrigeration systems such as absorber, desorber, solution heat exchanger etc. In this section absorption refrigeration cycle configurations of the investigations reviewed in the present work are discussed. The principle of operation and the use of membrane contactors in the desorber of absorption refrigeration systems can alter the configuration of the cycle. However, the use of membrane contactors in the absorber has no significant effect on the configuration of the cycle. Ali and Schwerdt (2009 and 2010), Ali (2010a or 2010b or both), Yu et al. (2012) and Isfahani et al. (2013) or Isfahani and Moghaddam (2013) [To check] used the plates-and-frames membrane module absorber with the same configuration of the conventional single-effect water-LiBr absorption cycle as shown in Figure 1 (a). Schaal et al. (2008) and Chen et al. (2006) used the conventional configuration of the single-effect ammonia-water absorption refrigeration cycle using hollow fiber membrane module absorber as shown in Figure 1 (b). The no-conventional cycle configurations used in the investigations reviewed in this work are herein discussed.
...riment with the starting reading for the plastic container as it read 43.1°C. This was obviously a miscalculation or delay by the Tain equipment and the probe settled down on the next reading. There is also a good explanation to why the first beaker in the first experiment, that had the milk poured in first, was rasing in temperature during the first 3 minutes. This is likely to be due to thermal layers in the hot coffee water when the milk is first poured in. When this beaker was stirred the temperature could have risen as hotter coffee was merging with the same layer the probe was testing. The only way to confirm this explanation is to complete an experiment where there are two beakers of coffee and they have milk poured into them however only one of them get stirred. Overall there would have been no problems with the volumes as I made sure all of the beakers had the same amount of coffee as the other beakers in that experiment. A good experiment to try would be one where there are two beakers of coffee filled to the brim. Then place cling wrap over one beaker, don't put any on the other beaker and then record their temperature to see how evaporation plays a part with heat loss.
In warmer climates such as Egypt they used techniques as evaporative cooling, “if water is placed in shallow trays during the cool tropical nights, its rapid evaporation can cause ice to form in the trays, even if the air does not fall below freezing temperatures”. Although refrigeration developed in the 18th century it wasn’t until the mid-19th century when the first refrigerator built using vapor technology was build by American John Gorrie in 1844. A few years later commercial refrigeration was introduced as well as vapor compression technology which was the beginning of our modern refrigeration. Later that century ammonia was popularized as the evaporation chemical in refrigeration. All the trials and tribulations of refrigeration where all stepping stones to the 20th century and the introduction of modern refrigeration as we know it
Central air units incorporates 2 main parts: the condenser, sometimes placed outside the house on a concrete block, and also the evaporator, situated simply higher than the chamber within the plenum (the giant metallic assembly covering the chamber and evaporator units). The evaporator is cooled by the condenser employing a special fluid known as Freon; while not Freon, there's no cooling.
Fossil fuels, such as coal and oil, are Carbon rich compounds, the combustion of which produces Carbon Dioxide, a pollutant and a greenhouse gas. A large amount of energy is released during this process, which is why the pollutants off products are tolerated. This process occurs constantly throughout the world, in power stations, vehicles and cooking ovens, leading to an immense volume of CO2 being released every second, 50% of which is absorbed by oceans (Oce...
Hairspray. Refrigerators. Air conditioners. These everyday luxuries, while making human life more comfortable, are taxing our health seriously. Clorofluorocarbons, or CFCs, are anthropogenic chemicals used in refrigerants and as propellants in aerosols. CFCs, also known as freons, are also the primary culprit behind the depletion of stratospheric ozone, which allows harmful ultraviolet rays to reach the Earth and its inhabitants.
Mechanical based heat pumps systems all have some common components: a compresser, a condenser, and an evaporator. The whole system is made of pipes that circulate a fluid that allows the transfer of heat. The evaporator is what transfer heat from the air in the room to the fluid inside of the system of pipes. The condenser is what takes the heat from the fluid and transfers it to the air outside.
The purchase of credits is a short term option for all companies producing electricity and steam regardless of the type of fossil fuel used. Present research has concentrated their evaluations on coal since coal produces the highest emissions of CO2. The following is the emissions of CO2 per Btu of energy based on fuel type is : Coal (anthracite) 228.6, Coal (bituminous) 205.7, Coal (lignite) 215.4, Coal (subbituminous) 214.3, Diesel fuel & heating oil161.3, Gasoline157.2, Propane139.0, and Natural gas117.0. Since natural gas is principally methane, it has higher energy thus lower CO2 compared to other fuels. This lower generation of CO2 has limited the interest in research to reduce the CO2 that is in the stack exhaust. However, the cost of engineering, construction, and operating any of the options
Refrigeration Refrigeration is defined as “The process of removing heat from an enclosed space, or from a substance, to lower its pressure.” (First website given in bibliography) In simpler terms, it is removing heat from states of matter in order to keep them cooler. The basic need for refrigeration is to cool food and beverages, as they often get spoilt if the temperature is high. Before actual refrigerators and other such mechanical systems were introduced, it was very common for people to cool their food with ice and snow.
Refrigeration, the production of cold, is an essential practice for present-day living. It is used in a many place like the processing and preservation of food, conditioning of air for comfort, manufacture of chemicals and other materials, cooling of concrete, medical applications etc. Refrigeration is defined as the science of maintaining the temperature of a particular space lower than its surrounding space. Refrigeration and air conditioning involves various processes such as compression, expansion, cooling, heating, humidification, de-humidification, air purification, air distribution etc. In all these processes, there is an exchange of mass, momentum and energy. All these exchanges are subject to certain fundamental laws. Hence to understand and analyses the refrigeration and air conditioning systems, a basic knowledge of the laws of thermodynamics, fluid mechanics and heat transfer is essential.
Life changed immensely in the 20th century as air conditioning and refrigeration systems became more efficient and controllable. Air Conditioning and Refrigeration play important roles in providing human comfort, food processing, storage, and many other industrial processes. We chose this topic because our life would be difficult without AC and Refrigeration. This paper will talk about the history of air conditioning and refrigeration, the role of engineers in designing and building it, people’s life before and after air conditioning and refrigeration, and finally Applications in the area of achievements and future developments.