This can be understood more by looking at the Carnot cycle encased in a saturation curve figure 2. The temperature at this state is still above the surrounding temperature. The compressor is shown at the bottom on the back of the refrigerator. The gages should also be calibrated by manufactures. Human error is a key in reading the gage properly. When measuring the pressure of the refrigerant the Bourdon gage was used.
Throttling valves are used rather than isentropic expansion engines which expand saturated liquids as there is only a small amount of work output to be gained — the costs for an engine would not be justifiable. The refrigeration cycle removes heat from the air and rejects it to the environment, acting as a reverse heat engine — commonly called a heat pump. The absorption system is powered by engine waste heat. Liquid Line It carries the liquid refrigerant from the receiver and conveys it to the expansion valve. The Vapor Compression Refrigeration Cycle The diagram at the left shows the components of a vapor-compression refrigeration cycle: a compressor, condenser, expansion valve, and evaporator. This absorption process occurs in the regenerator. Finally, the high pressure, high temperature liquid leaving the condenser is cooled and reduced in pressure by passing it through an expansion valve.
The difference between these values was said to be due to the unit being badly insulated hence the refrigerant absorbed heat from the environment as well as the air. The experiment was conducted within a 2 hour session, this time constraint limited the time that could be used for stabilisation of the unit. Heat transfer to the surrounding, can be minimized by insulating the exposed piping and especially the condenser and evaporator. Discharge Line It conveys the high pressure and high temperature refrigerant from the compressor to the condenser. R12 Temperature: Temperature °C Before Expansion valve 33 After Expansion valve 0 After Evaporator 21. Thus the proposed countermeasures should be investigated to reduce the potential of inaccuracy in obtaining measured data.
It is seen that point 1a is in the superheated region in the p-h diagram, meaning the evaporator has heated the refrigerant more than is expected. The temperatures of the air were relatively close to the aimed values, though the final temperature of the air was 2. In the proposed system, the compressor compresses the vapor only to 50-60% of the final pressure, while the additional compression is provided by a jet device using internal potential energy of the working fluid flow. Vapor-Compression Refrigeration Cycle This refrigeration cycle is approximately a Rankine cycle run in reverse. The boilers and refrigerator units are turned on and allowed to stabilise for about 5 minutes.
The application of this technology will be for more efficient designs of: 1 Industrial chillers, 2 Refrigeration plants, 3 Heat pumps, 4 Gas Liquefaction plants, 5 Cryogenic systems. The discharge action of the compressor is replaced by a generator. It cuts fuel consumption by 30% by combining an internal combustion engine with a mechanical compression refrigeration system and an absorption refrigeration system. The data obtained from the graph is shown in table 5 below. Between station B and C electric pre-heaters and steam injection occurs to bring the air to the conditions of a warm humid climate. In this lab dichlorofluoroethane R141b was used as the refrigerant, and the mass flow rate of water coming into the evaporator and the condenser was varied.
Measurement Equipment The measurement equipment used in the laboratory consisted of the thermometer for measuring temperature; Bourdon gages to measure pressure of the refrigerant, analogue voltmeter and ammeter to measure voltage and amperage into the apparatus. In the ideal refrigeration cycle it is assumed that the pressure drops are negligible, the compression is isentropic, the evaporator and condenser are adiabatic. This provides the input to the evaporator which was the first step of the cycle described above. The importance of this will be discussed when calculating the cooling load on the refrigerant later in section. Equipment The source of errors in the lab came from the measurement equipment.
The reading of the measurement is also critical since the temperature must be read from the bottom of the meniscus. This means that more cooling is needed to cool the superheated refrigerant to a saturated vapour, and also represents an irreversibility in the cycle. The condensation process occurs at essentially constant pressure. The devices that produce refrigeration are called refrigerators and the working fluids are called refrigerants. I go over how the Basic Refrigeration Cycle works from where the refrigerant enters the vapor compressor as it goes completely through the system, what the saturated state is, what superheat, total superheat, and subcooling are, as well as other detailed comments as we go through the system. Note that this is larger than the cooling load calculated for the air 2. From point 2 to point 3, the vapor travels through part of the condenser which removes the superheat by cooling the vapor.
The diagram in Figure 2. Heat pumps are machines which move heat from a lower temperature reservoir called the source to a higher temperature reservoir called the heat sink driven by a work input. A digital scale may have increased the precision of the results obtained though this would require adjustment on the unit. Refrigeration can be classified as: 1. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. The primary goal of this project was to make significant technical advances toward highly efficient liquefaction of hydrogen.
Process 3 to 4 is irreversible due to the nature of the air conditioning unit, this was discussed in Section 4 — Theory of Vapour Compression Refrigeration Cycles. It sends its compressed, high temperature vapor output through the condenser coils at the back of the refrigerator, where heat is given off to the air outside the refrigerator. However, the apparatus in the laboratory was possibly left insinuated to allow the student to see the contents of the condenser and evaporator. Then, the refrigerant is compressed adiabatically, so the fluid leaves the compressor under high pressure and with a high temperature. A simple comparison calculation would be the percentage decrease in thermal efficiency of the actual versus the ideal cycle. This is calculated using equation 2 below and we obtain a power of 2.