US2019264962A1PendingUtilityA1
A method for controlling pressure and oil level in an oil receiver of a vapour compressions system
Est. expiryJun 24, 2036(~9.9 yrs left)· nominal 20-yr term from priority
F25B 43/02F25B 31/002F25B 2700/1932
43
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Claims
Abstract
A method for controlling a valve arrangement ( 10 ) interconnecting at least one oil separator ( 8 ) and an oil receiver ( 9 ) in a vapour compression system ( 1 ) is disclosed. A pressure difference between a pressure prevailing inside the oil separator(s) ( 8 ) and a pressure prevailing inside the oil receiver ( 9 ) is obtained. Then a duration for an open time of an open/close sequence of the valve arrangement ( 10 ) is derived, based on the obtained pressure difference, and the valve arrangement ( 10 ) is controlled in accordance with the derived duration of an open time. The supply of oil to the oil receiver ( 9 ) can be accurately controlled, regardless of the operating conditions.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A method for controlling a valve arrangement interconnecting at least one oil separator and an oil receiver, the valve arrangement, the oil separator(s) and the oil receiver being arranged in a vapour compression system, the vapour compression system further comprising at least one compressor, a heat rejecting heat exchanger, an expansion device and an evaporator, arranged along a refrigerant path, wherein each oil separator is connected to an outlet of the compressor(s) and the oil receiver is connected to an oil supply inlet of each of the compressor(s), the method comprising the steps of:
obtaining a pressure difference between a pressure prevailing inside the oil separator(s) and a pressure prevailing inside the oil receiver, deriving a duration for an open time of an open/close sequence of the valve arrangement, based on the obtained pressure difference, and controlling the valve arrangement in accordance with the derived duration of an open time.
2 . The method according to claim 1 , wherein the step of obtaining a pressure difference comprises measuring the pressure prevailing inside the oil separator(s) and the pressure prevailing inside the oil receiver, and deriving the pressure difference from the measured pressures.
3 . The method according to claim 2 , wherein the step of deriving the pressure difference comprises estimating a current pressure prevailing inside the oil receiver, based on the measured value of the pressure prevailing inside the oil receiver.
4 . The method according to claim 1 , wherein the step of deriving a duration for an open time comprises selecting a duration which is decreasing as a function of increasing pressure difference.
5 . The method according to claim 1 , wherein the step of deriving a duration for an open time comprises consulting a graph or a look-up table.
6 . The method according to claim 1 , wherein the step of deriving a duration for an open time comprises calculating the duration, using a formula of the kind:
Δ
t
=
k
·
ρ
d
ρ
u
·
1
Δ
p
,
where Δt is the duration for the open time, k is a constant, ρ d is the density of fluid received in the oil receiver, ρ u is the density of fluid leaving the oil separator(s), and Δp is the obtained pressure difference.
7 . The method according to claim 1 , wherein the vapour compression system comprises at least two oil separators, wherein the valve arrangement is arranged to separately control fluid flow from each of the oil separators to the oil receiver, and wherein the method further comprises the step of selecting one of the oil separators, and the step of controlling the valve arrangement comprises controlling a valve interconnecting the selected oil separator and the oil receiver in accordance with the derived duration of an open time.
8 . The method according to claim 7 , wherein the step of selecting one of the oil separators comprises the steps of:
obtaining an oil level in each of the oil separators, obtaining an oil level in the oil receiver, and comparing the oil level in the oil receiver to a predefined threshold value, in the case that the oil level in the oil receiver is below the threshold value, selecting the oil separator having the highest oil level, and in the case that the oil level in the oil receiver is above the threshold value, selecting the oil separator having the lowest oil level.
9 . The method according to claim 1 , further comprising the step of controlling a supply of oil from the oil receiver to each of the compressors.
10 . The method according to claim 9 , wherein the step of controlling a supply of oil from the oil receiver to each of the compressors comprises the steps of:
obtaining a pressure difference between a pressure prevailing inside the oil receiver and a suction pressure for the compressor(s), deriving a duration for an open time of an open/close sequence of a valve arrangement interconnecting the oil receiver and the compressor(s), based on the obtained pressure difference, and controlling the valve arrangement interconnecting the oil receiver and the compressor(s) in accordance with the derived duration of an open time.
11 . The method according to claim 1 , further comprising the steps of:
supplying a pulse of fluid from an oil separator to the oil receiver by opening at least one valve of the valve arrangement for a predefined duration, monitoring a pressure prevailing inside the oil separator in response to the supplied pulse of fluid, and determining whether oil or gas was supplied from the oil separator to the oil receiver, based on the monitored pressure.
12 . The method according to claim 2 , wherein the step of deriving a duration for an open time comprises selecting a duration which is decreasing as a function of increasing pressure difference.
13 . The method according to claim 3 , wherein the step of deriving a duration for an open time comprises selecting a duration which is decreasing as a function of increasing pressure difference.
14 . The method according to claim 2 , wherein the step of deriving a duration for an open time comprises consulting a graph or a look-up table.
15 . The method according to claim 3 , wherein the step of deriving a duration for an open time comprises consulting a graph or a look-up table.
16 . The method according to claim 4 , wherein the step of deriving a duration for an open time comprises consulting a graph or a look-up table.
17 . The method according to claim 2 , wherein the step of deriving a duration for an open time comprises calculating the duration, using a formula of the kind:
Δ
t
=
k
·
ρ
d
ρ
u
·
1
Δ
p
,
where Δt is the duration for the open time, k is a constant, ρ d is the density of fluid received in the oil receiver, ρ u is the density of fluid leaving the oil separator(s), and Δp is the obtained pressure difference.
18 . The method according to claim 3 , wherein the step of deriving a duration for an open time comprises calculating the duration, using a formula of the kind:
Δ
t
=
k
·
ρ
d
ρ
u
·
1
Δ
p
,
where Δt is the duration for the open time, k is a constant, ρ d is the density of fluid received in the oil receiver, ρ u is the density of fluid leaving the oil separator(s), and Δp is the obtained pressure difference.
19 . The method according to claim 4 , wherein the step of deriving a duration for an open time comprises calculating the duration, using a formula of the kind:
Δ
t
=
k
·
ρ
d
ρ
u
·
1
Δ
p
,
where Δt is the duration for the open time, k is a constant, ρ d is the density of fluid received in the oil receiver, ρ u is the density of fluid leaving the oil separator(s), and Δp is the obtained pressure difference.
20 . The method according to claim 2 , wherein the vapour compression system comprises at least two oil separators, wherein the valve arrangement is arranged to separately control fluid flow from each of the oil separators to the oil receiver, and wherein the method further comprises the step of selecting one of the oil separators, and the step of controlling the valve arrangement comprises controlling a valve interconnecting the selected oil separator and the oil receiver in accordance with the derived duration of an open time.Join the waitlist — get patent alerts
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