Abstract: The invention is a process for determining the charge level of a vapor cycle environmental control system, having a condenser, evaporator, and an expansion valve, comprising the steps of providing a neural network having four input neurons, two hidden neurons and one output neurons; determining the number of degrees below the saturation temperature of the liquid refrigerant exiting the condenser and providing this measurement to the first input neuron; sensing the condenser sink temperature and providing the measurement to the second input neuron; sensing either the refrigerant outlet temperature from the condenser or the evaporator exhaust air temperature and providing the measurement to the third input neuron, sensing the evaporator inlet temperature and providing the measurement to the fourth input neuron; and using the trained neural network to monitor the charge level in the system.

Abstract: The invention is a process for determining the charge level of a vapor cycle environmental control system, having a condenser, evaporator, and an expansion valve, comprising the steps of providing a neural network having four input neurons, two hidden neurons and three output neurons; determining the number of degrees below the saturation temperature of the liquid refrigerant: exiting the condenser and providing this measurement to the first input neuron; sensing the condenser sink temperature and providing the measurement to the second input neuron; sensing either the refrigerant outlet temperature from the condenser or the evaporator exhaust air temperature and providing the measurement to the third input neuron, sensing the evaporator inlet temperature and providing the measurement to the fourth input neuron; and using the trained neural network to monitor the charge level in the system.

Abstract: A compensation device receives an inlet fluid flow and adjusts the pressure at an outlet so as to maintain a constant Reynolds number throughout the operating temperature range of the fluid. This is accomplished by a metering valve device in the nature of a fluted pin which becomes displaced in response to fluid temperature variations. This displacement varies the exposed cross-sectional area of a fluted end of the pin as it becomes seated to a greater or lesser extent in response to temperature variations. This results in corresponding changes in pressure between the inlet and outlet of the device while maintaining a constant Reynolds number. An additional embodiment includes an unfluted pin which becomes seated in a fluted bore located in a removable knurled knob. This allows one to insert various knurled knobs with fluted bores which have geometric configurations particularly adapted for particular fluids. Such a modular approach avoids the necessity of dismantling the device.