Stirling Cycle Refrigerator Sample Essay

Thermodynamic rhythm can be divided into two that are power rhythm and infrigidation rhythm. The rhythm that produce net sum of plant is called power rhythm. The power rhythm that can stay it working fluid in gaseous stage is called gas power rhythm. There are many types of rhythm in gas power rhythm such as Otto rhythm. Diesel rhythm. Bryton rhythm. Stirling rhythm and Ericson rhythm. The Otto rhythm is known as ideal rhythm for spark-ignition rhythm while the Diesel rhythm is known as compression-ignition internal burning engine. The Bryton rhythm is known as ideal rhythm for the modern-gas turbine engineand can be categorize as one of the gas power rhythm. The Bryton rhythm itself has four internal reversible procedures. The following rhythm is Stirling rhythm. This Stirling rhythm involves an isothermal heat-addition procedure and isothermal heat-rejection procedure. .

In reversed of heat engine. it has infrigidation system. Refrigeration system is the transportation system for heat from low temperature part to higher temperature part. The device that produces infrigidation is called icebox. heat pump and air-conditioning. The rhythm they operate is called infrigidation rhythm. The icebox and heat pump operate on the same rhythm but different with their aim. The aim of icebox is to keep the refrigerated infinite at low temperature. Dispatching this heat to a higher-temperature medium is simply a necessary portion of the operation. But the aim of heat pump is to keep het infinite at high temperature by absorbing the heat from a low temperature beginning and so providing that heat to high temperature medium such as house.

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The infrigidation rhythm can be divided into two that is vapor compaction infrigidation rhythm and gas infrigidation rhythm. In vapor compaction infrigidation rhythm. the refrigerant is vaporized and condensed alternately. This rhythm is the modified of the Rankine rhythm runing in contrary. It besides can be the Reversed Carnot Cycle operates on the reversed direc tion. For the gas infrigidation rhythm. the refrigerants remain in the gaseous stage throughout the full rhythm. The Reversed Stirling Cycle and the Reversed Bryton Cycle can be categorized in this gas infrigidation system. The Reversed Stirling Cycle is the rhythm of Stirling icebox operated.

1. 2Stirling Cycle Refrigerator

Stirling Cycle Refrigerator is one of the machine that runing on the Stirling rhythm machine. In Stirling rhythm. it has two popular rhythms that are Stirling rhythm engine and Stirling rhythm icebox. The operation of the Stirling rhythm involves an isothermal heat-addition procedure and isothermal heat -rejection procedure. It different from the Carnot procedure. The two isentropic procedures are replaced by two changeless -volume regeneration procedure. In the Stirling rhythm machine. it has five constituents that are working gas. heat-exchangers. displacer mechanism. regenerator. and expansion/compression mechanism. The working gas is trapped within the system. Stirling rhythm has heat-exchangers that are heat absorbing heat-exchanger and heat rejecting heat-exchanger. Heat absorbing heat-exchange is used to reassign heat from outside system to the working gas. while heat rejecting heat-exchanger is used to reassign the heat from the working gas to the outside system. Displacer mechanism is used to travel the working gas between the hot and cold terminal of the machine.

The map of regenerator is as a thermic barrier between the hot and cold terminals of the machine. Regenerator besides can be a ‘thermal store’ for the rhythm. The map of expansion/compression mechanism is to expands or/and compress the working fluid and it besides can bring forth net work end product that is used to travel the heat from low to high temperature part.

Many advantages of Stirling rhythm engine and Stirling rhythm icebox. Stirling rhythm engine has a changeless high efficiency. low noise comparison with other internal burning merchandise and can theoretically be a really efficient engine to change over heat to mechanical work at carnot efficiency. Stirling rhythm icebox can be used over a broad temperature scope. good efficiency for a big capacity. concentration and long life clip. The working gas in the Stirling rhythm icebox can be air. He or H. This working gas has no ozone depletion potency and nothing planetary warming possible. It is different for domestic icebox that utilizing CFCs and HCFCs that can do planetary heating and ozone depletion. The Stirling rhythm icebox besides can cool-down the nutrient below 30?C for the long clip.

Stirling rhythm icebox normally use a piston-cylinder. in either ? or ? constellation. A ?-configuration machine uses two Pistons which displace and expand/compress the gas at the same clip. A ?-configuration machine has a separate displacer-piston and expansion/compression Piston ( normally called a power-piston ) . In ?-configuration. the first procedure is enlargement under an isothermal status. At this phase. low-pressure working gas was expands isothermally at cold terminal temperature and absorb heat from the cold infinite. Second procedure is isochoric supplanting. The displacer-piston transportations all the working fluid through the regenerator to the hot terminal of the machine. Heat is delivered to the gas when it passes through the regenerator and makes the temperature of the gas raised at the hot infinite. When the temperature rises. gas force per unit area was increased significantly.

The 3rd procedure is isothermal compaction. The power Piston making work and compresses the gas at hot terminal temperature. After that. it rejects the heat to the hot infinite. The last procedure is isochoric supplanting. The displacer Piston transportations all the working gas isochorically through the regenerator to the cold and of the machine. Heat is absorbed from the gas as it passes through the regenerator. therefore take downing the temperature of the gas at cold infinite. When the temperature reduces. the gas force per unit area was bead and the system returns o it initial conditions.

There are two types of Stirling rhythm icebox that is V-type built-in Stirling icebox ( VISR ) and the split type-displacer Stirling icebox ( STFSR ) . The different between these two types is it driving mechanism of the displacer. The displacer for the V-type built-in Stirling icebox is straight driven by a motor through a crank-shaft mechanism. For the split type-displacer Stirling icebox. the displacer is driven by the fluid force or gas force per unit area which is produce indirectly by the Piston gesture and the shot and it besides depends on the operating conditions. Many analyses have been done on the V-type built-in Stirling icebox. They have been investigated about the power ingestions and the coefficient of public presentation. But non so much analysis has been done for the split type free-displacer Stirling icebox.

Many researches have studied about the Stirling rhythm icebox with respect of their application and have found that are many factor affect the public presentation of the Stirling rhythm icebox.

1. 3Objective

• To analyze a mathematical theoretical account of V-type Stirling rhythm for infrigidation system. • To acquire a conceptual design of V-type Stirling rhythm for infrigidation syste

1. 4Scope

This research is accompanied with Scopess to guarantee the undertaking will accomplish the aim and non transcend within its intended boundary. There are few Scopess that have to be followed. The Scopess that have been set are ;

• Study about Stirling rhythm
• Identify the general construct of thermodynamic rhythm for the Stirling rhythm icebox. • Make literature reappraisal on Stirling rhythm for icebox. • Solve mathematical theoretical account for Stirling rhythm icebox utilizing ideal gas jurisprudence equation and ordinary differential equation ( ODE ) • Simulate the mathematical theoretical account for Stirling rhythm icebox. • Propose the conceptual design of Stirling rhythm icebox.


2. 1Introduction

The original stirling rhythm engine was invented. developed and patented in 1816 by the Scots curate Dr. Robert Stirling with aid from his brother that is engineer. The engine that was build by him was so heavy and complicated. The engine is build for usage in hot-air engine as alternate to the steam engine. After that. many probes have been made on stirling rhythm. In 1834. John Herschel was suggested that this stirling engine could be used as a icebox and after that Alexander Kirk was constructed the
foremost stirling rhythm icebox in 1864.

From that minute. many developments have been made on stirling ice chest. Today. stirling ice chest are used in many application. The development in stirling ice chest design besides was turn up until today.

2. 2Thermodynamic Analysis

In thermodynamic analysis. the first things that need to understand is how this V-type Stirling rhythm icebox operates. In general. the V-type Stirling rhythm icebox has 4 thermodynamic procedures as shown in Figure 3. 2 and Figure 3. 3.

Process 1-2: Compaction Procedure
Work is expended to compact the gas while it is chiefly in the compaction volume.

Process 2-3: Cooling Procedure
The gas is moved from the compaction volume to the enlargement volume. On its manner the gas is cooled so that it has a temperature near that to the ice chest when it arrives in the enlargement volume. This chilling takes topographic point at changeless volume and causes the force per unit area to diminish.

Process 3-4: Expansion Procedure
The cooled gas is expanded in the enlargement volume. The enlargement causes a farther lessening in temperature. Less work. than was needed for compaction. can be extracted from the enlargement because the force per unit area is lower.

Process 4-1: Heating Procedure
The cold gas is moved back from the enlargement volume to the compaction volume. On its manner the gas is heated so that it has a temperature near that to the warmer when it arrives in the compaction volume. The warming occurs at changeless volume and causes the force per unit area to increase. The rhythm can now be repeated by get downing with the procedure 1-2.

2. 3Type of Application for Stirling Cycle Refrigerator

Today. many application have been made on Stirling rhythm icebox including • Heat daze trial device
• Freezing desiccant
• Thermal belongings trial device
• Blood/cell storage-devices
• Cold ice chest
• Household usage as a deep-freeze and icebox
• As solar-powered Stirling rhythm icebox

The survey in theory and experiment of the stirling rhythm icebox has been discuss by many research worker. Assortment of methodological analysis has been used to analyze this stirling icebox. A survey in theory is needed to do the simulation of it existent state of affairs when this stirling icebox operates. It besides needs some mathematical faculty. Meanwhile. the survey that been made by experiment need an apprehension on the process of the experiment to acquire the perfect consequence. Because of that. literature reappraisal must be made to more understand the survey of stirling icebox in theory and experiment. For this literature reappraisal. four diaries have been selected. Two of the diaries are for V-type Stirling rhythm icebox. Another two diaries are for power-piston Stirling rhythm icebox The V-type Stirling rhythm icebox use ?-configuration that has two Pistons which displace and expand or compact the gas at the same clip. The power-piston Stirling rhythm icebox use ?-configuration that has a separate displacer-piston and enlargement or compaction Piston.

2. 2Literiture Review on V-Type Stirling Cycle Refrigerator

Sun Le’an. Zhoa Yuanyang. Li Liansang and Shu Pengchang ( 2008 ) have been discoursing about the public presentation of a paradigm Stirling domestic icebox. They was investigated the thermic public presentation of the V-type Stirling rhythm icebox. The working fluid that was used on this paradigm is helium and N. The temperature scope that was used is over -20 to -60 ?C. They make this survey to optimal the design and operation of the V-type Stirling rhythm icebox when it is applied to the domestic infrigidation system. In this paradigm. the cold caput is installed between the enlargement port and the regenerator and the electric warmer covers the cold caput. The compaction and enlargement Pistons are driven by a crank-shaft mechanism working with a fixed stage between compaction and enlargement procedures. They have done the experiment trial on the paradigm of V-type Stirling rhythm icebox. They used He and N as a working gas. In this experiment. they use three sorts of constellation ( Table 1 ) .

The charged force per unit area for the He and N is from 0. 25 Mpa to 1. 4 Mpa and the rotational velocity frequence was 10-40 Hz. They besides have done the theoretical analysis and computing machine simulation on the thermodynamic procedure. The consequence from the simulation was comparison with the consequence from the experiment trial. From their experiment. the chilling capacity is much greater for He than N because of it specific heat capacity is larger than N and the flow opposition of He is much smaller than N. The force per unit area loss for N is larger than the He. Other consequence is the chilling capacity additions with rotational velocity and COP has a upper limit when utilizing He as a working fluid. But it different for N. the chilling capacity and COP have an optimum. The optimal rotational velocity for COP is from 500-700 revolutions per minute for N and 800-1000 for He.

They have make decision that each constituent must be matched each other to acquire the needed specifications and to obtain optimum constellation for V-type Stirling rhythm icebox constituent. They besides choose the He as a working fluid because the He is better than N. Another decision is the optimal rotational velocity for the chilling capacity is different between N and He. The COP has a peak value about 900 revolutions per minute for He and 600 revolutions per minute for N.

|Configurations |1 |2 |3 | |Regenerator length ( millimeter ) |80 |60 |50 | |Regenerator diameter ( millimeter ) |55 |50 |40 |

Table 1: The specifications for three constellations of the regenerator

O. Ercan Ataer and H. Karabulut ( 2004 ) have discussed about thermodynamic analysis of the V-type Stirling rhythm icebox. They have divided the V-type Stirling rhythm icebox into 14 fixed volumes that is enlargement and compaction infinites. ice chest. warmer and regenerator. Each control volume in the V-type icebox is an unfastened system subjected to a periodic mass flow. The preservation of mass and energy equation are written for each control volume of the icebox. A computing machine plan is written in FORTRAN. and the equations are solved iteratively. They have calculated the COP and work done of V-type Stirling rhythm icebox in numerical analysis. They besides calculate the mass. temperature and denseness of the working fluid for each control volumes. A simplified iterative numerical method is developed to work out the equations of the V-type Stirling rhythm icebox. In this survey. they were used air as the working fluid. They besides used the different charge force per unit areas in this thermodynamic analysis of V-type Stirling rhythm icebox. The charge force per unit area that was used is taken between 2 and 5 saloon.

From their consequence. the sum of work done and chilling rate of the machine are 3. 05 and 4. 37 J per rhythm. Other consequence is the COP is lessening when the charge force per unit area increases. This happens due to increase in cyclic work. The wall temperature of enlargement infinite besides decreases with charge force per unit area. They have made decision that the charge force per unit area higher than 2 saloon will diminish the COP of the Stirling rhythm icebox and the 2nd decision is increased in the heat transportation countries and the heat transportation coefficients causes addition in the COP of the machine.

2. 3Literature Review on Power Piston Stirling Cycle Refrigerator

Emre Oguz and Fatih Ozkadi have done the experimental probe on a Stirling rhythm cooled domestic icebox. They choose a paradigm of a free Piston Stirling ice chest from private company to incorporate into domestic icebox cabinet. They use thermosyphon system as a heat transportation mechanism. The paradigm was tested with different charge measures of refrigerant. They used R134a as the refrigerant in the thermosyphon system. The experiment besides used different input electromotive force for the ice chest. Helium had been chosen as the working gas in the free Piston Stirling ice chest. The frequence that they used for this experiment is 1Hz. A fan was placed in the cabinet to increase the convective heat transportation coefficient. The ambient temperature is 25 ± 0. 5°C for all trials. During the specified steady-state intervals. the temperatures inside the cabinet are good within ± 0. 3°C for 240 minute trials and ± 0. 7°C for the trials that last longer than 1000 proceedingss. They have recoded the temperature of cold side thermosyphon. the temperatures of the shelves for the cabinet and the input power of the Stirling ice chest during paradigm is being tested. They besides calculated the evaporator mercantile establishment. capacitor mercantile establishment and recess. and Stirling ice chest for warm and cold caput temperatures.

The consequence from that experiment is the cold caput. vaporization and mean cabinet temperatures decreases as the input electromotive force of the Stirling ice chest increased. Other consequence is COP was addition as the cold caput temperature increases at changeless warm caput and drive electromotive force status. There besides has three parametric quantities that can give consequence to infrigidation capacity and thermic public presentation that is cold caput temperature. the warm caput temperature and input electromotive force. But input electromotive force does non give any consequence to the COP. The decision that they make from this experiment is the COP value can be higher than 2. 5 at the certain operating conditions depending on the cold and warm caput temperatures. Other decision is free Piston Stirling ice chests can be integrated into domestic icebox cabinets in several ways including the thermosyphon system and the forced air convection heat transportation mechanism. This method besides can be preferred for both cold and warm sides of the ice chest because there are no extra constituents devouring energy in the thermosyphon system. But more theoretical and experimental research is needed on thermosyphon systems to gauge the heat transportation and force per unit area bead.

Bancha Kongtragool and Somchai Wongwises ( 2005 ) have made a thermodynamic analysis of a Stirling engine including dead volume of hot infinite. cold infinite and regerator. Although this analysis was done on stirling engine. but the construct and the theory from this analysis can be used in Stirling rhythm ice chest to happen the dead volume. The aim of this survey to analysis an imperfect regeneration Stirling engine with dead volume based on the classical thermodynamics. They have developed an isothermal theoretical account for an imperfect regeneration Stirling engine. That engine besides includes dead volume of hot infinite. cold infinite and regenerator. They besides make numerical simulation on regenerator effectivity and dead volumes. The effects from the simulation have being studied. The consequence from that survey is the mass of the working fluid merely depend on dead volume.

It increases with increasing of dead volume. The compaction work. enlargement work and engine web lessening with increasing dead volume. It means that a big dead volume requires a little sum of compaction work and gives a little sum of enlargement work. An engine with big dead volume besides will bring forth merely a little sum of engine web. For a perfect regenerator. the external heat input and end product is non required and the entire heat input decreases with increasing dead volume. An imperfect regenerator requires external heat input. However. the entire heat input is like to increase with increasing of dead volume. The entire heat input besides addition with diminishing regenerator effectivity. The decision that they make for this analysis is the Stirling engine with a given dead volume. an inefficient regenerator will non impact the engine web if the regenerator effectual temperature is an arithmetic mean of the warmer and the ice chest temperature. But. an engine with an inefficient regenerator needs more heat input and better chilling than an efficient one.

Figure 3. 3: temperature-entropy diagram

Figure 3. 2: Pressure-volume diagram


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