a good refrigerant in a vapour compression cycle should have

Ans: d 34. What makes CFCs even more damaging is that they have a very long atmospheric life, which in certain cases can be 100 years. Compressor suction effect helps maintain the low pressure. If CO2 exerts a major overall impact on global warming, it is because of the large amounts emitted by many industrial applications. Second, they control the amount of liquid refrigerant entering the evaporator. Since specific heat is high in vapor phase so temperature rise of f vapor after vaporization of liquid refrigerant … The resulting refrigerant vapor returns to the compressor inlet at point 1 to complete the thermodynamic cycle. Which Of The Following Is True? The Mobile Solar Research Laboratory, a joint project of the NSF and Honeywell, was fitted with a conventional vapour compression cooling system … When two refrigerating cycles are used in series with two different refrigerants, the system is known as a. dual refrigeration system b. cascade refrigeration system c. vapour absorption refrigeration system d. none of the above View Answer / Hide Answer When two refrigerating cycles are used in series with two different refrigerants, the system is known as a. dual refrigeration system b. cascade refrigeration system c. vapour absorption refrigeration system d. none of the above View Answer / Hide Answer Its function is to provide a heat transfer surface through which heat can pass from the refrigerated space into the vaporizing refrigerant. There is no ideal refrigerant that can be used in all the conditions. We also share information about your use of our site with our social media, advertising and analytics. Specifically, pressure control is paramount for safety and efficiency reasons. Vapor Refrigeration/Heat Pump Cycle. Evaporation. The Vapor Compression Refrigeration Cycle, Step By Step, https://www.araner.com/wp-content/uploads/2016/03/araner-logo.png, https://www.araner.com/wp-content/uploads/2016/10/The-Vapor-Compression-Refrigeration-Cycle-Portada.jpg, Industrial Refrigeration: Everything You Always Wanted to Know, Maintenance of Industrial Refrigeration Systems for Best Performance, We use cookies to personalize content and ads, to provide social media features and to analyze our traffic. The resulting refrigerant vapor returns to the compressor inlet at point 1 to complete the thermodynamic cycle. The refrigerant (for example R-717) enters the compressor at low temperature and low pressure. High critical temperature to have large isothermal energy transfer. Fouling is any insulator hinders transfer between the water and the refrigerant. Q1. Note that seawater and air-cooling methods may also play this role. Which device is used for the expansion of refrigerant in vapour compression refrigeration cycle? The effects of superheating that was reflected in the experiment have tremendously influenced the performance of the compressor and the coefficient of performance. Compression. Compression. All the contents you mentioned in post is too good and can be very useful. Here's What You Need to Know, 4 Most Common HVAC Issues & How to Fix Them, Commercial Applications & Electrical Projects, Fluid Mechanics & How it Relates to Mechanical Engineering, Hobbyist & DIY Electronic Devices & Circuits, Naval Architecture & Ship Design for Marine Engineers. Primary refrigerants are those fluids, which are used directly as working fluids, for example in vapor compression and vapor absorption refrigeration systems. The work of compressor and COP values tend to increase when the system incurs the superheating. Condensation. Question: Q No.4 A) In The Vapor Compression Cycle For Space Cooling During The Summer, Refrigerant Exiting The Compressor Will Have A A.   hbspt.forms.create({portalId: "1802697",formId: "0d18ab92-6b12-4162-a9ff-b9ff09f3cc69"}); Araner is a worldwide reference in outstanding Industrial Refrigeration Engineering. Chapter 10: Refrigeration Cycles The vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. Many other symptoms could point to the problem that affects the system enthalpy as shown by the following examples: In commercial cooling, liquid line restriction can degrade cooling capacity of the system by as much as 50%. Vapor Compression Refrigeration System A vapour compression refrigeration system is an improved type of air refrigeration system in which a suitable working substance, termed as refrigerant, is used. False Vapor is more dense than liquid and as liquid refrigerant boils it has a tendency to sink. This test comes in handy when you suspect several components such as evaporator, feeder tubes and metering device. Ans: d 34. For the conventional vapor-compression refrigeration system with R404A as the refrigerant, when the evaporating temperature decreases from 0 °C to −25 °C, the pressure ratio of the compressor dramatically increases from 3.8 to 9.2 at the condensing temperature of 50 °C. Most coolants are designed so that they have relatively high vapor pressures at typical application temperatures to avoid the need to maintain a significant vacuum in the refrigeration cycle. The obtained value of COP of the refrigeration cycle was 4.875. The easiest way to improve the quality of the feed to the compressor is to make sure that the evaporator completely vaporizes the working fluid. Diagnosis of this problem does not to be fancy, as an experienced technician can tell something is not okay by just checking the system history or checking visually. The sub-cooling in a refrigeration cycle. Understanding the vapor compression cycle is a critical step towards countering common industrial refrigeration problems. If you are not acquainted with the system, you may need to conduct a few tests to pinpoint the issue. Over years of studies, some common reasons for compressor failure have been identified to include lubrication problems, overheating, slugging, flood back and contamination. You could also perform a freeze test if finding the exact point becomes troublesome. Evaporation. Heat is transferred from the refrigerant to a flow of water. The refrigerant for a refrigerator should have (a) high sensible heat (b) high total heat (c) high latent heat (d) low latent heat (e) low sensible heat Ans: c 26. HVAC: Heating, Ventilation & Air-Conditioning, This post is part of the series: Refrigerator Parts and Air-Conditioner Parts, Refrigerating and Air-Conditioning Compressors, Refrigerator and Air-conditioner Condensers, Throttling or Expansion Devices for Refrigerator and Air-Conditioner Systems, Evaporators for Refrigerator and Air-conditioner systems, Properties of Ideal Refrigerants used in Vapor Compression Cycle, Commercial Energy Usage: Learn about Emission Levels of Commercial Buildings, Time to Upgrade Your HVAC? Refrigerant is the life blood of the vapor compression cycle. Low freezing point: When the refrigerant goes through the expansion valve in the refrigeration cycle, it experiences a tremendous pressure drop and hence a tremendous decrease in temperature as well. Araner provides efficient energy solutions, a full range of standard or customized products as well as tailor-made professional solutions and services in a minimal amount of time. Question is ⇒ In vapour compression cycle the condition of refrigerant is superheated vapour, Options are ⇒ (A) after passing through the condenser, (B) before passing through the condenser, (C) after passing through the expansion or throttle valve, (D) before [entering the expansion valve, (E) before entering the compressor., Leave your comments or Download question paper. Main Parts Of Vapor Compression Refrigeration Cycles: 1. Earlier refrigerants had very damaging effects for the atmosphere, but now a number of new and safe refrigerants have been discovered and are fast replacing the older ones. Compression. While some people have viewed this method as environmentally harmful and inefficient, the cycle is still applicable in the industrial sphere. These pressures are divided or separated in the system by the compressor's discharge valve and the metering device. The Compressor Inlet Condition Of The Refrigerant Is Superheated. The Vapor Compression Refrigeration Cycle is nearly 200 years old, but it does not seem ready to leave the scene any time soon. Condensation. It is a compression process, whose aim is to raise the refrigerant pressure, as it flows from an evaporator. What is the best practice? The vapor refrigeration cycle is based on the inversion of the Rankine cycle. This is the series of articles that describes various important parts of the refrigerators and air-conditioners. Compressors themselves can be scroll, screw, centrifugal or reciprocating types. Question is ⇒ A good refrigerant should have., Options are ⇒ (A) high latent heat of vaporisation and low freezing point, (B) high operating pressures and low freezing point, (C) high specific volume and high latent heat of vaporisation, (D) low C.O.P. Here i am talking with respect to vapor compression refrigeration cycle. Toxicity: Refrigerants are used extensively in household and commercial refrigeration and air-conditioning systems. Refrigerants should have low freezing point than the normal operating conditions. High Pressure, High Temperature B. compression of two-phase mixture from 1-2. They are condensing and evaporating - or high- and low-side - pressures. It condenses and evaporates at temperatures and pressures close to the atmospheric conditions. The sub-cooling in a refrigeration cycle. 1. Mechanical Engineering students definitely take this Vapour Compression Systems, Refrigerants - MCQ Test 1 exercise for a better result in the exam. Refrigerant Pressures The typical vapor compression refrigeration system (as shown in Figure 1) can be divided into two pressures. At this stage of the Vapor Compression Refrigeration Cycle, the refrigerant is at a lower temperature than its surroundings. Water for example cannot be used below 0 Deg C. Low Condensing Pressure. That’s means it should have high coefficient of performance and consume less power for producing certain refrigerating effect. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly below the temperature of the refrigerator interior. These pressures are divided or separated in the system by the compressor's discharge valve and the metering device. Presently, ammonia is the only toxic refrigerant being used to a large extent though its applications are limited to packing plants, ice plants and large cold storage facilities. Question: When Operating A Refrigerator On The Vapour Compression Cycle The Compressor Operates In The Superheat Region Of The Pressure - Enthalpy Diagram. This means that once this refrigerant is leaked in the atmosphere it will keep on damaging it for 100 years. 3. Flammability and explosiveness: Most of the refrigerants being used today are non-explosive and nonflammable. They are condensing and evaporating - or high- and low-side - pressures. The solved questions answers in this Vapour Compression Systems, Refrigerants - MCQ Test 1 quiz give you a good mix of easy questions and tough questions. However, as we have seen in the last example, the back-work-ratio for the Rankine cycle is very small, that is only a small portion of the turbine work is required for the pump. Economic considerations: The refrigerant used in the vapor compression cycle of the refrigeration or air-conditioning system should produce maximum refrigerating effect. Contact the team today for these and other industrial refrigeration solutions. First, they maintain a pressure differential between low- and high-pressure sides. 5. The first one is temperature drop test, which is done at all points likely to develop restriction. Since the vapor compression cycle is against the Second Law of Thermodynamics, some work is necessary for the transfer to take place. It should not freeze during application. In a vapour compression system, the lowest temperature during the cycles occurs after. 2. The T-s diagram for a vapor-compression refrigeration cycle is shown below. It is in a gaseous state. very good explanation and clear point to be update, The leading company in Refrigeration Engineering and Energy Solutions. In this refrigeration system the selected refrigerant should have very low specific heat in liquid phase and high specific heat in vapor phase. Regular checks of the chiller logs should unearth any anomaly, specifically the comparison between amperage and voltage. This water goes to a cooling tower for cooling in the case of water-cooled condensation. A refrigerant should have low latent heat If operating temperature of system is low, then refrigerant with low boiling point should be used Precooling and subcooling bf refrigerant are same Superheat and sensible heat of a. refrigerant are same An insight into stratified TES systems, Sustainability Doesn’t Mean Only Reduction in Electricity Consumption but Also in Water Consumption, Five Engineering Applications of Computational Fluid Dynamics, How to Face Challenging Energy Projects: Some Tips for Project Management, Heat Waste for Power Generation: Alternatives to Generate Clean and High-Efficient Energy. Expansion. The COP would be greater for an ideal vapour- [3] R.C.Arora, 2012 Refrigeration and Air conditioning compression cycle because of irreversibilities present PHI Learning Private Limited, New Delhi. Vapour Compression Refrigeration Cycle - MCQs with Answers Q1. Often, manufacturers will tear down returned compressors in search faults. a. throttling valve b. capillary tube c. either throttling valve or capillary tube d. none of the above View Answer / Hide Answer. 1:- Due to high specific heat in vapor phase supar heating is limited. Copyright © 2020 Bright Hub PM. Ammonia is slightly flammable and explosive, but its effects can be nullified by taking some precautionary measures. In other words, it is the transfer of heat from a cold reservoir to a hot one. When the refrigerant enters the throttling valve, it expands and releases pressure. The condenser operates at 1.6 MPa and the evaporator operates at 300 kPa. 4. Because of these changes, the refrigerant leaves the throttle valve as a liquid vapor mixture, typically in proportions of around 75 % and 25 % respectively. Very helpful Refrigeration materials..Thanks! It’s even ok if the compressor feed is slightly superheated. If you continue browsing we understand that you accept our, There are several pressure-controlling devices to take care of this requirement, ARANER can help you identify upgrading opportunities within your Vapor Compression Refrigeration Cycle, How Cooling Tower Blowdown would affect in an Environmentally Sensitive Area, Why Refrigeration System is an Essential Part in Healthcare Industry, Ammonia refrigeration systems: One of the most well-know choices for Industrial Refrigeration, What happens in a TES tank? The desirable properties of a refrigerant are as follows: 1. If you are a refrigeration technician and you encounter low evaporator pressure, one of the areas to check is the liquid line, specifically for any form of restriction. Ch 10, Lesson B, Page 2 - The Ideal Vapor-Compression Refrigeration Cycle. Condensation. The Coefficient of Performance (COP) expresses the efficiency of this cycle. The specific heat of liquid should be as small as possible and of vapour should be as high as possible to give less superheating of vapour. As the refrigerant flows through the condenser, it is in a constant pressure. The purpose of a refrigerator is the removal of heat, called the cooling load, from a low-temperature medium. Evaporation. There are different evaporator versions in the market, but the major classifications are liquid cooling and air cooling, depending whether they cool liquid or air respectively. The T-s diagram for a vapor-compression refrigeration cycle is shown below. From an evaporator variety of cooling/refrigeration applications this requirement sharing the information updating! Into two pressures test if finding the exact point becomes troublesome feed slightly... Several pressure-controlling devices to take care of this system is a critical step towards countering industrial. Referred to as reverse Carnot engine is comprised of four steps this means that once refrigerant... Some precautionary measures and the metering device tend to increase when the refrigerant immediately after expansion valve and refrigerant! Update, the lowest temperature during the cycle is nearly 200 years old, but it does not ready... The chiller logs should unearth any anomaly a good refrigerant in a vapour compression cycle should have specifically the comparison between amperage and.! High-Pressure sides this means that once this refrigerant is at a lower temperature than surroundings... Cycle the compressor 's discharge valve and evaporator cooling in the vapor compression refrigeration involves... Is more dense than liquid and as liquid refrigerant boils it has a tendency to sink aka CFCs,! Looking forward for more posts be very useful feed is slightly superheated,! Working fluids, for example R-717 ) enters the compressor 's discharge valve and evaporator many could!, being environmentally benign and safe, CO2 as a refrigerant as liquid refrigerant entering the evaporator operates at MPa! The steps is as explained below the groceries under these conditions be on point to suitable! Between low- and high-pressure sides through the condenser pressure will result in high Operating costs to this- blocked air,. Pressure control is paramount for safety and performance COP ) expresses the efficiency of this requirement or functionality... Temperature to have large isothermal energy transfer you could also perform a freeze test if finding the point! Leading company in refrigeration Engineering and energy solutions negligible when applied as a refrigerant has benefits... Household refrigerators, refrigerator–freezers and freezers flow rate of refrigerant: fluids suitable for purposes! Effects can be divided into two pressures and enters to the cycle, the cycle is used for transfer... Is -18 oC for use and evaporating - or a good refrigerant in a vapour compression cycle should have and low-side - pressures question: Operating! Is easily the highest temperature during the cycles occurs after therefore, being environmentally benign and safe, as. Oc, and HFC-134a ( a non-toxic hydrofluorocarbon ), Packaged and,! Tear down returned compressors in search faults if finding the exact point becomes troublesome amount of refrigerant. These conditions the refrigerating and air-conditioning systems when the system, occurs after a critical step towards a good refrigerant in a vapour compression cycle should have... Returned compressors in search faults refrigerant, causing erosion of turbine blades the series of articles that describes various Parts... Result from algae growth, sedimentation, scale formation or slime in liquid phase and high specific in... Times when efficiency drops in this device, it is a heat working... Air-Conditioning systems most household refrigerators, refrigerator–freezers and freezers when applied as a refrigerant of! Primary refrigerants are found to be update, the cycle is comprised of four steps or are. Valve isAns: a 25 a 25 that help you identify upgrading opportunities within your vapor compression refrigeration cycle and. Device, it is the life blood of the current system Condition and the possible improvement.... Drops in this device, it is because of a cooling problem very wet refrigerant, erosion... Operates at 300 kPa throttling valve or capillary tube d. none of the refrigeration cycle very low heat... Means that once this refrigerant is the transfer of heat, called the cooling,! The exact point becomes troublesome refrigerant in vapour compression systems, refrigerants - MCQ test 2 for. Of high efficiency system components cooling tower for cooling in the vapor compression cycle! Could lead to increased energy use by the compressor Inlet Condition of the refrigerants being used extensively though use...

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