Method for controlling ejector capacity in a vapour compression system
AssigneeDanfoss A/S
InventorsLars Finn Sloth Larsen, Jan Prins, Kenneth Bank Madsen
Life of this patent
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Abstract
A method for controlling ejector capacity in a vapour compression system (1) is disclosed. A parameter value being representative for a flow rate of liquid refrigerant from the evaporator(s) (8, 10) and into a return pipe (12, 13) is obtained, and the capacity of the ejector(s) (6) is adjusted based on the obtained parameter value. Ejector capacity may be shifted between low pressure ejectors (liquid ejectors) (6a, 6b, 6c, 6d) and high pressure ejectors (gas ejectors) (6e, 6f).
Claims15
A method for controlling at least one ejector in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, at least one ejector, a receiver, at least one expansion device and at least one evaporator arranged in a refrigerant path, wherein the at least one ejector is arranged in the refrigerant path with a primary inlet of the at least one ejector connected to an outlet of the heat rejecting heat exchanger, an outlet of the at least one ejector connected to the receiver and a secondary inlet of the at least one ejector connected to a part of a return pipe receiving refrigerant from outlets of the at least one evaporator, the method comprising the steps of:
- obtaining a pressure value of refrigerant leaving the heat rejecting heat exchanger, and/or a temperature value of refrigerant leaving the heat rejecting heat exchanger, and/or an ambient temperature value,
- controlling at least the pressure of the at least one ejector based on the obtained pressure value and/or temperature value, and
- calculating a pressure ratio:
- Pprimary−Poutlet/Psecondary/Poutlet
- where Pprimary is a pressure prevailing at the primary inlet of the at least one ejector, Poutlet is a pressure prevailing at the outlet of the at least one ejector and PSecondary is a pressure prevailing at the secondary inlet of the at least one ejector, and wherein the step of controlling at least the pressure of the at least one ejector is further performed on the basis of the calculated pressure ratio.
A method for controlling at least one ejector in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, at least one ejector, a receiver, at least one expansion device and at least one evaporator arranged in a refrigerant path, wherein the at least one ejector is arranged in the refrigerant path with a primary inlet of the at least one ejector connected to an outlet of the heat rejecting heat exchanger, an outlet of the at least one ejector connected to the receiver and a secondary inlet of the at least one ejector connected to a part of a return pipe receiving refrigerant from outlets of the at least one evaporator, the method comprising the steps of:
- obtaining a pressure value of refrigerant leaving the heat rejecting heat exchanger, and/or a temperature value of refrigerant leaving the heat rejecting heat exchanger, and/or an ambient temperature value, and
- controlling at least the pressure of the at least one ejector based on the obtained pressure value and/or temperature value,
- wherein the step of controlling at least the pressure of the at least one ejector comprises preventing a flow of refrigerant from the outlet of the heat rejecting heat exchanger to the primary inlet of the at least one ejector in the case that the pressure of refrigerant leaving the heat rejecting heat exchanger is above a predefined pressure threshold level and/or the temperature of refrigerant leaving the heat rejecting heat exchanger is above a predefined temperature threshold level, and
- wherein the step of controlling at least the pressure of the at least one ejector comprises increasing a capacity of the pressure of the at least one ejector in the case that the calculated pressure ratio is below a predefined threshold level.
A method for controlling at least one ejector in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, at least one ejector, a receiver, at least one expansion device and at least one evaporator arranged in a refrigerant path, wherein the at least one ejector is arranged in the refrigerant path with a primary inlet of the at least one ejector connected to an outlet of the heat rejecting heat exchanger, an outlet of the at least one ejector connected to the receiver and a secondary inlet of the at least one ejector connected to a part of a return pipe receiving refrigerant from outlets of the at least one evaporator, the method comprising the steps of:
- obtaining a pressure value of refrigerant leaving the heat rejecting heat exchanger, and/or a temperature value of refrigerant leaving the heat rejecting heat exchanger, and/or an ambient temperature value, and
- controlling at least the pressure of the at least one ejector based on the obtained pressure value and/or temperature value,
- wherein the step of controlling at least the pressure of the at least one ejector comprises preventing a flow of refrigerant from the outlet of the heat rejecting heat exchanger to the primary inlet of the at least one ejector in the case that the pressure of refrigerant leaving the heat rejecting heat exchanger is above a predefined pressure threshold level and/or the temperature of refrigerant leaving the heat rejecting heat exchanger is above a predefined temperature threshold level, and
- wherein the step of controlling at least the pressure of the at least one ejector comprises allowing a flow of refrigerant from the outlet of the heat rejecting heat exchanger to the primary inlet of the at least one ejector in the case that the pressure of refrigerant leaving the heat rejecting heat exchanger is below a predefined pressure threshold level and/or the temperature of refrigerant leaving the heat rejecting heat exchanger is below a predefined temperature threshold level.
A method for controlling at least one ejector in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, at least one ejector, a receiver, at least one expansion device and at least one evaporator arranged in a refrigerant path, wherein the at least one ejector is arranged in the refrigerant path with a primary inlet of the at least one ejector connected to an outlet of the heat rejecting heat exchanger, an outlet of the at least one ejector connected to the receiver and a secondary inlet of the at least one ejector connected to a part of a return pipe receiving refrigerant from outlets of the at least one evaporator, the method comprising the steps of:
- obtaining a pressure value of refrigerant leaving the heat rejecting heat exchanger, and/or a temperature value of refrigerant leaving the heat rejecting heat exchanger, and/or an ambient temperature value, and
- controlling at least the pressure of the at least one ejector based on the obtained pressure value and/or temperature value,
- wherein the step of controlling at least the pressure of the at least one ejector comprises preventing a flow of refrigerant from the outlet of the heat rejecting heat exchanger to the primary inlet of the at least one ejector in the case that the pressure of refrigerant leaving the heat rejecting heat exchanger is above a predefined pressure threshold level and/or the temperature of refrigerant leaving the heat rejecting heat exchanger is above a predefined temperature threshold level, and
- further comprising the step of obtaining a refrigerant pressure at an outlet of the at least one ejector and wherein the step of controlling at least the pressure of the at least one ejector is further based on a pressure difference and/or a pressure ratio between the refrigerant pressure at the primary inlet of the at least one ejector and the refrigerant pressure at the outlet of the at least one ejector.
A method for controlling at least one ejector in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, at least one ejector, a receiver, at least one expansion device and at least one evaporator arranged in a refrigerant path, wherein the at least one ejector is arranged in the refrigerant path with a primary inlet of the at least one ejector connected to an outlet of the heat rejecting heat exchanger, an outlet of the at least one ejector connected to the receiver and a secondary inlet of the at least one ejector connected to a part of a return pipe receiving refrigerant from outlets of the at least one evaporator, the method comprising the steps of:
- obtaining a pressure value of refrigerant leaving the heat rejecting heat exchanger, and/or a temperature value of refrigerant leaving the heat rejecting heat exchanger, and/or an ambient temperature value,
- controlling at least the pressure of the at least one ejector based on the obtained pressure value and/or temperature value,
- wherein the step of controlling at least the pressure of the at least one ejector comprises allowing a flow of refrigerant from the outlet of the heat rejecting heat exchanger to the primary inlet of the at least one ejector in the case that the pressure of refrigerant leaving the heat rejecting heat exchanger is below a predefined pressure threshold level and/or the temperature of refrigerant leaving the heat rejecting heat exchanger is below a predefined temperature threshold level, and
- further comprising the step of obtaining a refrigerant pressure at an outlet of the at least one ejector, and wherein the step of controlling at least the pressure of the at least one ejector is further based on a pressure difference and/or a pressure ratio between the refrigerant pressure at the primary inlet of the at least one ejector and the refrigerant pressure at the outlet of the at least one ejector.
A method for controlling at least one ejector in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, at least one ejector, a receiver, at least one expansion device and at least one evaporator arranged in a refrigerant path, wherein the at least one ejector is arranged in the refrigerant path with a primary inlet of the at least one ejector connected to an outlet of the heat rejecting heat exchanger, an outlet of the at least one ejector connected to the receiver and a secondary inlet of the at least one ejector connected to a part of a return pipe receiving refrigerant from outlets of the at least one evaporator, the method comprising the steps of:
- obtaining a pressure value of refrigerant leaving the heat rejecting heat exchanger, and/or a temperature value of refrigerant leaving the heat rejecting heat exchanger, and/or an ambient temperature value,
- controlling at least the pressure of the at least one ejector based on the obtained pressure value and/or temperature value, and
- obtaining a refrigerant pressure at the secondary inlet of the at least one ejector and a refrigerant pressure at an outlet of the at least one ejector,
- wherein the step of controlling at least the pressure of the at least one ejector is further based on a pressure difference and/or a pressure ratio between the refrigerant pressure at the secondary inlet of the at least one ejector and the refrigerant pressure at the outlet of the at least one ejector.
Dependencies are inferred from the claim text.