A generic simulation of energy consumption of automobile air conditioning systems
- Authors: Konz, Martin
- Date: 2003
- Subjects: Automobiles -- Air conditioning
- Language: English
- Type: Thesis , Masters , MTech (Engineering)
- Identifier: vital:10822 , http://hdl.handle.net/10948/129 , Automobiles -- Air conditioning
- Description: The air conditioning system in a car is, in addition to the heating system, installed to increase the comfort in the passenger compartment. Comfort is not the only reason for automotive air conditioning systems, as road safety also improves with the comfort of the driver, as a pleasant environment reduces driver fatigue. The rising environmental problems and, hence, resulting stringent legislation are forcing the automobile industry to develop cars with ever decreasing fuel consumptions. The question of better fuel consumption and energy utilisation does not stop with the engine and aerodynamics, but is required of the air-conditioning system as well. Thus, incessantly innovative technologies are developed to decrease the energy required by the air-conditioning systems. The interaction of the refrigerant cycle components and the rapidly changing operating conditions of the car (speed, revolutions per minute, etc.) places extensive demands on the control system. In addition, the air-conditioning system is also designed for high ambient temperatures (cool down), but is mostly used in fairly moderate conditions. This operation allows for energy saving control strategies such as externally controlled compressors, blower motor control, etc. The experimental comparison of different air-conditioning systems, components or control strategies is very time consuming and extensive, and the use of an air-conditioned wind tunnel is inevitable when experiments need to be done with reproducible ambient conditions.This, combined with the high costs of installation and operation of a wind tunnel is a major problem. Furthermore, the effect of component or control strategy enhancements should be available as soon as possible in the early stages of design. The above considerations have prompted the rapid development of new powerful simulation tools, but in most cases the simulation tools are focused on one specific component or problem only. A more holistic approach would be to combine the calculations of two or more programs. This implies the adaptation of the model to more programs which leads to a lack of transparency. Obviously, the entire development work cannot be done entirely by simulation, especially in the later phases of the development where it would still be necessary to build prototypes to evaluate the done work experimentally. However, in the early stages of development, it would be advantagous to work without expensive prototypes.
- Full Text:
- Date Issued: 2003
- Authors: Konz, Martin
- Date: 2003
- Subjects: Automobiles -- Air conditioning
- Language: English
- Type: Thesis , Masters , MTech (Engineering)
- Identifier: vital:10822 , http://hdl.handle.net/10948/129 , Automobiles -- Air conditioning
- Description: The air conditioning system in a car is, in addition to the heating system, installed to increase the comfort in the passenger compartment. Comfort is not the only reason for automotive air conditioning systems, as road safety also improves with the comfort of the driver, as a pleasant environment reduces driver fatigue. The rising environmental problems and, hence, resulting stringent legislation are forcing the automobile industry to develop cars with ever decreasing fuel consumptions. The question of better fuel consumption and energy utilisation does not stop with the engine and aerodynamics, but is required of the air-conditioning system as well. Thus, incessantly innovative technologies are developed to decrease the energy required by the air-conditioning systems. The interaction of the refrigerant cycle components and the rapidly changing operating conditions of the car (speed, revolutions per minute, etc.) places extensive demands on the control system. In addition, the air-conditioning system is also designed for high ambient temperatures (cool down), but is mostly used in fairly moderate conditions. This operation allows for energy saving control strategies such as externally controlled compressors, blower motor control, etc. The experimental comparison of different air-conditioning systems, components or control strategies is very time consuming and extensive, and the use of an air-conditioned wind tunnel is inevitable when experiments need to be done with reproducible ambient conditions.This, combined with the high costs of installation and operation of a wind tunnel is a major problem. Furthermore, the effect of component or control strategy enhancements should be available as soon as possible in the early stages of design. The above considerations have prompted the rapid development of new powerful simulation tools, but in most cases the simulation tools are focused on one specific component or problem only. A more holistic approach would be to combine the calculations of two or more programs. This implies the adaptation of the model to more programs which leads to a lack of transparency. Obviously, the entire development work cannot be done entirely by simulation, especially in the later phases of the development where it would still be necessary to build prototypes to evaluate the done work experimentally. However, in the early stages of development, it would be advantagous to work without expensive prototypes.
- Full Text:
- Date Issued: 2003
An automotive carbon dioxide air-conditioning system with heat pump
- Authors: Böttcher, Christof
- Date: 2003
- Subjects: Automobiles -- Air conditioning , Automobiles -- Heating and ventilation , Heat pumps
- Language: English
- Type: Thesis , Masters , MTech (Mechanical Engineering)
- Identifier: vital:10811 , http://hdl.handle.net/10948/206 , Automobiles -- Air conditioning , Automobiles -- Heating and ventilation , Heat pumps
- Description: The refrigerant circuits of car air-conditioning systems are fitted with so-called open type compressors, because there is only a lip seal preventing the refrigerant from leaking from the compressor housing to the atmosphere. In addition, the cycle uses damping elements between the compressor and the other components on the suction and pressure lines to reduce vibration and noise transfer from the engine to the car body. Both the lip seal and damping elements result in loss of refrigerant as they are made from elastomers and leak with age, and, under high temperature conditions inside the engine room, these elements also allow a relatively high permeation of the refrigerant gas to the atmosphere. With very high refrigerant losses in the older R12 -cooling cycles and the damage caused by this gas to the ozone layer in the stratosphere, the Montreal protocol phased out this refrigerant and the car industry was forced to revert completely to R134a until 1994/95. R134a has no ozone depletion potential, but it has a direct global warming potential, and, therefore, leakages also have to be minimised. R134a has, because of its molecular size, a high permeation potential and, hence, all the refrigerant hoses are lined internally. Unfortunately, these hoses also leak with age and significant refrigerant loss will occur [1] R134a can therefore only be viewed as a solution until an alternative refrigerant with no direct global warming potential has been developed. Candidates for new refrigerants are natural substances such as hydrocarbons or carbon dioxide [2]. Unfortunately, both substances have disadvantages and their use is restricted to special cases, for e.g. hydrocarbons are flammable and are not used in car air-conditioners, but in Germany it is used as a refrigerant in household refrigerators with hermetic cycles. What makes the implementation of carbon dioxide (CO2) difficult are the high system pressures and the low critical point [3].
- Full Text:
- Date Issued: 2003
- Authors: Böttcher, Christof
- Date: 2003
- Subjects: Automobiles -- Air conditioning , Automobiles -- Heating and ventilation , Heat pumps
- Language: English
- Type: Thesis , Masters , MTech (Mechanical Engineering)
- Identifier: vital:10811 , http://hdl.handle.net/10948/206 , Automobiles -- Air conditioning , Automobiles -- Heating and ventilation , Heat pumps
- Description: The refrigerant circuits of car air-conditioning systems are fitted with so-called open type compressors, because there is only a lip seal preventing the refrigerant from leaking from the compressor housing to the atmosphere. In addition, the cycle uses damping elements between the compressor and the other components on the suction and pressure lines to reduce vibration and noise transfer from the engine to the car body. Both the lip seal and damping elements result in loss of refrigerant as they are made from elastomers and leak with age, and, under high temperature conditions inside the engine room, these elements also allow a relatively high permeation of the refrigerant gas to the atmosphere. With very high refrigerant losses in the older R12 -cooling cycles and the damage caused by this gas to the ozone layer in the stratosphere, the Montreal protocol phased out this refrigerant and the car industry was forced to revert completely to R134a until 1994/95. R134a has no ozone depletion potential, but it has a direct global warming potential, and, therefore, leakages also have to be minimised. R134a has, because of its molecular size, a high permeation potential and, hence, all the refrigerant hoses are lined internally. Unfortunately, these hoses also leak with age and significant refrigerant loss will occur [1] R134a can therefore only be viewed as a solution until an alternative refrigerant with no direct global warming potential has been developed. Candidates for new refrigerants are natural substances such as hydrocarbons or carbon dioxide [2]. Unfortunately, both substances have disadvantages and their use is restricted to special cases, for e.g. hydrocarbons are flammable and are not used in car air-conditioners, but in Germany it is used as a refrigerant in household refrigerators with hermetic cycles. What makes the implementation of carbon dioxide (CO2) difficult are the high system pressures and the low critical point [3].
- Full Text:
- Date Issued: 2003
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