Abstract:
Methods and systems to manage refrigerant levels in a chiller system are provided. An evaporator of the chiller system may be configured to have a spill over port allowing oil containing refrigerant to spill over through the spill over port. The spill over port may be positioned at a place that corresponds to a desired refrigerant level in the evaporator. The spill over refrigerant may be directed into a heat exchanger that is configured to substantially vaporize refrigerant of the spill over refrigerant to a slightly superheat temperature. A method of maintaining a proper refrigerant level in the evaporator may include regulating a refrigerant flow to the evaporator so that the vaporized refrigerant of the spill over refrigerant is maintained at the slightly superheat temperature.
Abstract:
A home refrigerator (1) having two refrigeration compartments (3, 4), and a heat-pump cooling circuit (7) for maintaining two predetermined reference temperatures in the two compartments (3, 4); the cooling circuit (7) having a first (10) and a second (11) evaporator housed inside the two compartments (3, 4), and a condenser (9) housed outside the refrigerator (1); the outlet of the condenser (9) being connected to the inlet of the first evaporator (10) via a first refrigerant expansion member (19), an electrically controlled first on-off valve (20), a high-pressure refrigerant storage tank (22), and a non-return valve (23) arranged in series with one another; and the outlet of the condenser (9) being connected to the inlet of the second evaporator (11) via a second refrigerant expansion member (13) and an electrically controlled second on-off valve (14).
Abstract:
A method and apparatus are provided for indicating the status of the refrigerant charge in an air conditioning system based upon the degree of subcooling present in the condensed refrigerant system temperature measurements. The status of the refrigerant charge in the system is indicated in real-time on a service panel for access by a field service technician. The status of the refrigerant charge in the system on a time-average basis for a specified period of operation is presented on an indicator panel. The indicator panel includes a first indicator light indicating that the refrigerant charge is low, a second indicator light indicating that the refrigerant charge is high, and a third indicator light indicating that the refrigerant charge is correct.
Abstract:
Methods and apparatus are provided for determining refrigerant charge in a vapor compressor system (VCS) of an aircraft. The methods and apparatus comprise the following steps of, and/or means for, generating a data set from historical data representative of a plurality of VCS operating conditions over time, identifying one or more steady-state data points in the generated data set, forming a revised data set that includes at least the steady-state data points, using principal components analysis (PCA) to derive values for a plurality of minimally correlated input variables, supplying the derived values for the plurality of minimally correlated input variables and the corresponding values for the VCS refrigerant charge in the revised data set to a nonlinear neural network model, and deriving a simulator model characterizing a relationship between the plurality of minimally correlated input variables and the VCS refrigerant charge.
Abstract:
A refrigeration system comprising a compressor for compressing a refrigerant, a condenser for condensing refrigerant to a liquid, an evaporator for evaporating liquid refrigerant from the condenser to a gas, an inner control loop for optimizing a supply of liquid refrigerant to the evaporator, and an outer control loop for optimizing a level of refrigerant in the evaporator, said outer control loop defining a supply rate for said inner control loop based on an optimization including measurement of evaporator performance, and said inner control loop optimizing liquid refrigerant supply based on said defined supply rate. Independent variables, such as proportion of oil in refrigerant, amount of refrigerant, contaminants, non-condensibles, scale and other deposits on heat transfer surfaces, may be estimated or measured. A model of the system and/or a thermodynamic model approximating the system, for example derived from temperature and pressure gages, as well as power computations or measurements, is employed to determine or estimate the effect on efficiency of deviance from an optimal state. Various methods are provided for returning the system to an optimal state, and for calculating a cost-effectiveness of employing such processes.
Abstract:
A cooling cycle formed so as to improve the cooling performance thereof by allowing a liquid phase refrigerant to constantly exist in a gas-liquid separator even when a supercritical fluid is used as a refrigerant for a multiple effect cycle, wherein a main path (8) is formed by connecting a compressor (2), a radiator (3), a first throttle valve (4), a gas-liquid separator (5), a second throttle valve (6) and an evaporator (7) in series, and a bypass (9) for returning a gas phase refrigerant from the gas-liquid separator (5) to the compressor (2) is provided in this main path (8), the degree of opening of the first throttle valve (4) being reduced, when the liquid phase refrigerant in the gas-liquid separator becomes insufficient, to increase the degree of pressure reduction of the refrigerant passing through the gas-liquid separator, whereby the liquid phase refrigerant constantly exists in the gas-liquid separator.