Abstract:
A vapour compression system (1) comprising at least two evaporator groups (5a, 5b, 5c), each evaporator group (5a, 5b, 5c) comprising an ejector unit (7a, 7b, 7c), at least one evaporator (9a, 9b, 9c) and a flow control device (8a, 8b, 8c) controlling a flow of refrigerant to the at least one evaporator (9a, 9b, 9c). For each evaporator group (5a, 5b, 5c) the outlet of the evaporator (9a, 9b, 9c) is connected to a secondary inlet (12a, 12b, 12c) of the corresponding ejector unit (7a, 7b, 7c). The vapour compression system (1) can be controlled in an energy efficient and stable manner. A method for controlling the vapour compression system (1) is also disclosed.
Abstract:
A vapour compression system (1) comprising a compressor unit (2), a heat rejecting heat exchanger (4), an ejector (5), a receiver (6), an expansion device (7) and an evaporator (8) is disclosed. The vapour compression system (1) further comprises a non-return valve (9) arranged in the refrigerant path between an outlet (17) of the evaporator (8) and an inlet (15) of the compressor unit (2). The outlet (17) of the evaporator (8) is connected to a secondary inlet (16) of the ejector (5) and to the inlet (15) of the compressor unit (2), via the non-return valve (9), and a gaseous outlet (12) of the receiver (6) is connected to a part of the refrigerant path which interconnects the non-return valve (9) and the inlet (15) of the compressor unit (2). The non-return valve (9) ensures automatic control of refrigerant flow from the evaporator (8) towards the compressor unit (2) and the secondary inlet (16) of the ejector (5), and from the receiver (6) towards the compressor unit (2).
Abstract:
A method for determining a transit time (t t ) of an ultrasonic burst, in particular in an ultrasonic flow meter is described, said method comprising generating a first transmit signal having a first frequency and detecting a first receive signal, generating a second transmit signal having a second frequency different from the first frequency and detecting a second receive signal. Such method should allow to reliably detect the transit time with low costs. To this end a function of time based on characteristics of the two receive signals (10, 11) is used for determining the transit time.
Abstract:
A refrigerant valve arrangement (1) is shown comprising a housing (2) having an inlet (3) and an outlet (4) and defining a main flow direction (5) a first valve having a first valve axis (11), and a second valve having a second valve axis (17). Such a refrigerant valve arrangement should have a low pressure drop between inlet and outlet. To this end said first valve axis (11) encloses a first angle (a) smaller than 90° with said main flow direction (5) and/or said second valve axis (17) encloses a second angle (β) larger than 90° with said main flow direction (5).
Abstract:
A method for controlling a valve arrangement (12), e.g. in the form of a three way valve, in a vapour compression system (1) is disclosed, the vapour compression system (1) comprising an ejector (6). The valve arrangement (12) is arranged to supply refrigerant to a compressor unit (2) from the gaseous outlet (11) of a receiver (7) and/or from the outlet of an evaporator (9). The vapour compression system (1) may be operated in a first mode of operation (summer mode) or in a second mode of operation (winter mode). When operated in the second mode of operation, it is determined whether or not conditions for operating the vapour compression system (1) in the first mode of operation are prevailing. If this is the case, the valve arrangement (12) is actively switched to the first mode of operation by closing a first inlet (13) towards the evaporator (7) and fully opening a second inlet (14) towards the receiver (7).
Abstract:
A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising an ejector (5). The method comprises controlling a compressor unit (2) in order to adjust a pressure inside a receiver (6), on the basis of a detected pressure of refrigerant leaving an evaporator (8). The portion of refrigerant leaving the evaporator (8) which is supplied to a secondary inlet (15) of the ejector is maximised and the portion of refrigerant supplied directly to the compressor unit (2) is minimised, while ensuring that the pressure of refrigerant leaving the evaporator (8) does not decrease below an acceptable level.
Abstract:
A spool arrangement 1 is described comprising a spool member (47) having a coil embedded in a spool housing (48) made of plastic material and protection means (2, 13, 28) comprising at least two parts together forming a receiving volume (46), said spool member (47) being located in said receiving volume. Such a spool arrangement (1) should be used in an environment in which there is a risk of explosions. To this end said parts form protective walls on all sides of said receiving volume (46)
Abstract:
A method for estimating and/or controlling a temperature of foodstuff stored in a refrigerated cavity of a refrigeration system is disclosed. A time constant for the temperature of the foodstuff is established, said time constant being determined based on a time interval between a relatively large change of opening degree of an expansion valve and until variance of the opening degree of the expansion valve decreases to a relatively low variance. The time constant is applied to a low pass filter, said low pass filter providing a relation between the temperature of the foodstuff and the air temperature, and the low pass filter is applied to the monitored air temperature, thereby obtaining an estimate for the temperature of the foodstuff stored in the refrigerated cavity.
Abstract:
An expansion valve (1) for a vapour compression system, the valve (1) comprising a first valve part (5) having an outlet orifice (7) and a piston (8) movable inside the outlet orifice (7) in response to a differential pressure across the expansion valve (1), controlling a fluid flow through the first valve part (5). A cross-sectional flow area of the outlet orifice (7) between a circumference at an inner surface of the outlet orifice (7) and a circumference at an outer surface of the piston (8) varies as a function of the position of the piston (8) relative to the outlet orifice (7). A first cross-sectional flow area is defined at a first differential pressure, and a second cross-sectional flow area is defined at a second differential pressure, where the first cross-sectional flow area is smaller than the second cross-sectional flow area, and the first differential pressure is lower than the second differential pressure.
Abstract:
A solenoid valve (1, 101) is provided comprising a housing (2, 102), having an inlet and an outlet (6), wherein the solenoid valve also comprises a valve element (9, 109) and a valve seat (10, 110). To provide a solenoid valve to be used with high maximum operating pressure differences between inlet and outlet, the solenoid valve comprises at least one progressive spring (24), wherein the valve element is forced by the at least one progressive spring. Thereby, the spring force acting on the valve element in the closed position of the valve may be decreased, while still retaining a large spring force in the opened position of the solenoid valve.