CHAPTER 2
LITERATURE REVIEW
2 INTRODUCTION
Exergy is a term use in thermodynamic where also some terms found in the literature that are equivalent to: available energy, essergy, utilizable energy, available energy and availability. The exergy of the system is defined as the maximum useful work that can be done by the composite of the system and a specified in reference environment. The reference environment is assumed to be infinite, in equilibrium, and to enclose all other systems. Typically, the environment is specified by stating its temperature, pressure and chemical composition. Exergy is not simply a thermodynamic property, but rather is a property of both a system and the reference environment (Holman, 2009). Exergy can be destroyed by irreversibility of a process.
There have been several studies on the exergy analysis of vapor compression refrigeration cycle. (T. Hari Prasad, 2009) Investigation of coefficient of performance, and determine the second law efficiency vapor compression refrigeration cycle using R-12 as refrigerant based on exergy analysis. (X.Xu, 1992) It studied of exergy analysis on vapor compression refrigeration using R12, R134a and R290 as refrigerants. (Miguel Padilla, 2010) It presented the exergy analysis of the impact of the direct replacement R12 with the R134A on the performance of vapor compression refrigeration system. (Rahul ukey, 2012) In this study, it studied different refrigerant that can optimized the performance of the vapor compression refrigeration system by using exergy analysis (Yaser Sahebi, 2010) It studied efficiency effect the on economical by using exergy analysis on heat pump. (J. U. Ahamed, 2011) It showed in study on prospect of hydrocarbon based on exergy analysis in vap...
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... air pumping device (such as blower or axial flow fan) is across the tube bundle which may be either forced draft or induced draft as shown in the Figure 2.2. A support structure that high enough to allow air to enter beneath the air cooled heat exchanger.
2.4.3 Shell and tube heat exchanger
Figure 2.3 Shell and tube heat exchanger
From the Figure 2.3, shell and tube heat exchangers consist of a series of tubes. One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes that are being heated or cooled so that it can either provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned, etc. Shell and Tube heat exchangers are typically used for high pressure applications. This is because the shell and tube
Gadolinium and its performance were limited by the use of passive regenerators and heat exchangers in the refrigeration cycle [25]. So, a magnetic refrigeration device must utilize a regenerative process to produce a large enough temperature span to be useful for refrigeration purposes [26].
The air packed column was connected to the center packed column with medium length nipple and an elbow joint connected a copper pipe to a thin silicon pipe. At the same time a silicon pipe, attached to the air packed column, was connected to the air valve, and with a small nipple a control valve and flowmeter are attached. Then a small nipple attached to the flowmeter is connected to the pressure gauges where attached to the air packed tower.
to an unfavorable free energy change for the process. Once added to a system, before equilibrium
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
energy was given out or taken in. We can show this on a graph. Alcohol
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.
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.
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 factors for exponential growth for air-conditioning are the HVAC Market, energy, environment, communication, societal, political, preparing for the future, looking ahead, and the conclusion. Buildings of the U.S. use approximately 35% of the nation’s precise total of energy consumption. The worth of shipments by U.S. HVAC manufacturers was over $28 billion of 1996. Since there are 52,000 CHC chillers needed to be replaced among the U.S., there’s a large opportunity for new chillers, new technology for the HVAC industry. The ozone depletion is an international issue in which is currently being resolved. The 3rd world countries are still allowed to manufacture CFC’s. Illegal imports of CFC’S to the U.S. is a consistent concern. Many illegal imports are virgin CFC’s. Those whom have a political overtones are specifically the ones whom create a protectionism of local commerce, having a negative impact on those inside and out of the country.
Thermodynamics is the branch of science concerned with the nature of heat and its conversion to any form of energy. In thermodynamics, both the thermodynamic system and its environment are considered. A thermodynamic system, in general, is defined by its volume, pressure, temperature, and chemical make-up. In general, the environment will contain heat sources with unlimited heat capacity allowing it to give and receive heat without changing its temperature. Whenever the conditions change, the thermodynamic system will respond by changing its state; the temperature, volume, pressure, or chemical make-up will adjust accordingly in order to reach its original state of equilibrium. There are three laws of thermodynamics in which the changing system can follow in order to return to equilibrium.
The compressors used in refrigerators use titanium turbines. Using titanium needs high level of energy, which make the cost higher. One of the future techs that will help saving energy and reducing the cost is the refrigerant known as “R-718” or “Water Vapor”. R718 can be more efficient than our current refrigerants.
... temperature of 112 0C also and a pressure 2.5 bar. Cooling water is used to condense the vapor exiting column. Remaining methane and hydrogen are separated in reflux drum where the vapor stream is combined with other gases streams. The overhead of first and second separator are combined to form fuel gas. The liquid stream exiting in the bottoms of the reflux drum is pumped at pressure of 3.3 bar for discharging pressure. The pump stream is separated in two streams. One stream is to feed to tray one of the column and the other one stream is cooled down to 38 0C in heat exchanger. Then, the cooled product stream is sent to storage.
In thermodynamics Refrigeration is the major application area, in which the heat is transferred from a lower temperature region to a higher temperature region. The devices which produce refrigeration are known as Refrigerators and the cycle on which it operates are called refrigeration cycles. Vapour compression refrigeration cycle is the most regularly used refrigeration cycle in which the refrigerant is alternately vaporized and condensed and in the vapor phase it is compressed. Gas refrigeration cycle is the well-known refrigeration cycle in which cycle refrigerant remains in the gaseous phase throughout the cycle. Cascade refrigeration are the other refrigeration cycles discussed in this chapter; absorption refrigeration is the one more refrigeration cycle which is used where the refrigerant is dissolved in liquid before it is compressed. One more refrigeration in which refrigeration is produced by passing the electric current through two dissimilar materials is called as the thermoelectric refrigeration.
turbine via interceptor valves and control valves and after expanding enters the L.P. turbine stage via 2 numbers of cross over pipes. In the L.P. stage the steam expands in axially opposite direction to counteract the trust and enters the condenser placed directly below the L.P. turbine. The cooling water flowing throughout the condenser tubes condenses the steam and the condensate collected in the hot well of the condenser. The condensate collected is pumped by means of 3*50% duty condensate pumps through L.P. heaters to deaerator from where the boiler feed pump delivers the water to boiler through H.P. heaters thus forming a closed