Abstract: Oil is returned from the evaporator to the oil sump in a refrigeration chiller by directing the lubricant-liquid refrigerant mixture found in the chiller evaporator into heat exchange contact with relatively hotter system lubricant as such lubricant flows from the oil sump to the location of its use in the chiller's compressor. The oil flowing from the sump to the compressor rejects sufficient heat to the lubricant-liquid refrigerant mixture to induce the percolation thereof, such percolation being sufficiently energetic to cause slugs of the lubricant-liquid refrigerant mixture to be delivered from the location of heat exchange into the chiller's lubricant sump thereby effecting the return of oil from the evaporator for re-use in the compressor.

Abstract: A fresh air unit. The unit comprises: a housing having an airstream flowing therethrough; a pre-cooling portion, and dehumidification portion. The pre-cooling portion is located within the housing and reduces the temperature and specific humidity of a gas in the airstream to a target zone on a psychrometric chart. The dehumidification portion is also located in the housing downstream of the pre-cooling portion. The dehumidification portion removes a selected amount of moisture from the gas and reheats the gas a selected amount of sensible heat gain.

Abstract: Efficient two-phase refrigerant mixture distribution is accomplished in a falling film evaporator by use of a refrigerant distributor disposed internal of the evaporator shell which overlies the evaporator tube bundle and which internally causes said two-phase refrigerant mixture to be made available along essentially the entire length and across essentially the entire width of the tube bundle prior to the delivery of the refrigerant out of the distributor.

Abstract: A sensor system. The system comprises a binary sensor issuing a signal representative of a first or second condition; sampling circuitry, operatively connected to the binary sensor, for monitoring the number of transitions between the first and second conditions during a sampling period; integration circuitry for accumulating the sampled number of transitions over time; and signal generation circuitry for issuing an analog signal representative of the accumulated transitions.

Abstract: A refrigeration system includes a cooling coil and two variable speed heat exchanger wheels (an enthalpy wheel and a sensible wheel) whose rotational speeds are adjusted to control the humidity and temperature of a comfort zone as well as limit the minimum temperature of the cooling coil itself. Each wheel has one half extending across a supply air passageway and another half extending across a return air passageway to transfer heat between the supply air and the return air at a rate that increases with the speed of the wheel. The enthalpy wheel is near the intake and exhaust of outdoor air. The sensible wheel is near a supply air duct and a return air duct associated with the comfort zone. And the cooling coil is disposed in the supply air passageway between the two wheels. In response to a cooling demand, enthalpy wheel speed is adjusted to maintain a minimum coil temperature to avoid coil freeze-up, while sensible wheel speed is adjusted to meet the cooling load.

Abstract: A screw compressor employs a piston unloader disposed in a bore remote from the compressor's working chamber. Flow communication between the bore and working chamber is through a series of unloader ports. The unloader piston has an end portion of uniform geometry which causes the physically non-overlapping unloader ports to, in effect, overlap in operation and is such that the unloader piston need not be maintained in any specific orientation within the bore in which it resides in order to unload the compressor in a continuous fashion.

Abstract: A sensor system. The system comprises a binary sensor issuing a signal representative of a first or second condition; sampling circuitry, operatively connected to the binary sensor, for monitoring the number of transitions between the first and second conditions during a sampling period; integration circuitry for accumulating the sampled number of transitions over time; and signal generation circuitry for issuing an analog signal representative of the accumulated transitions.

Abstract: A board mount assembly. The assembly comprises a panel, a board mount and a circuit board. The panel is generally arranged in a plane. The board mount has an attachment portion operably connected to the panel and parallel thereto, and has a support portion extending from the first portion at a non-perpendicular angle relative to the plane of the panel. The circuit board has a first standoff engaged with the board mount.

Abstract: A single piece tip seal for use in scroll compressors is produced using a polyetheretherkeytone base material injected into a mold having two ingates to the mold cavity.

Abstract: A refrigeration system comprising: a duct; a compressor having an inlet and an outlet; a reheat coil located in the duct and having an outlet and an inlet operatively connected to the compressor outlet; and a condenser having an outlet, and an inlet operatively connected to the reheat coil outlet. The system also comprises an expansion device, an evaporator and a receiver system. The expansion device has an outlet, and an inlet operatively connected to the condenser outlet. The evaporator is located in the duct upstream of the reheat coil and has an inlet operatively connected to the expansion device outlet, and has an outlet operatively connected to the compressor inlet. The receiver system has an inlet operatively connected to the condenser outlet and has an outlet operatively connected to the evaporator inlet. The receiver system includes an upstream flow control device, a receiver and a downstream flow control device in series.

Abstract: An assured supply of lubricant to the compressor in a refrigeration chiller is provided by a reservoir that is connected in parallel with the main line by which lubricant is supplied to the compressor. The reservoir is connected to the main lubricant supply line in a manner such that if the lubricant supply line is blown dry, as can occur as a result of an unusual or abnormal chiller shutdown condition, a critical portion of the supply line will be refilled by the reservoir relatively very quickly which assures the immediate availability of lubricant to the compressor from that portion of the lubricant supply line when it next starts up.

Abstract: A condensate drain pan. The drain pan comprises a frame supporting a surface; a side outlet in the frame proximal a high point; and a bottom outlet in the surface proximal a low point. The surface is sloped so that the first side drains to the side outlet; the surface is sloped so that the second side drains to the bottom outlet; and the surface is sloped from the high point to the low point.

Abstract: In a preferred embodiment, a single motor drives both oil and refrigerant pumps in a refrigeration chiller, the motor and oil pump being disposed in the chiller's oil supply tank and the refrigerant pump being disposed exterior thereof. The refrigerant pump pumps liquid refrigerant to the chiller's compressor section so as to cool the motor by which the compressor is driven while the oil pump pumps oil to chiller locations that require lubrication when the chiller is in operation. A uniquely designed impeller permits low pressure liquid refrigerant in its liquid state to be reliably pumped to a location of use, without significant flashing, from a source location which is at a height only a short distance above the pump inlet. A stand alone refrigerant pump embodiment is also described.

Abstract: A method of mounting a compressor above a heat exchanger. The method comprises the steps of: attaching a transfer device to the exterior of the heat exchanger where the transfer device has a lower arc surface and an upper sloped surface; positioning the compressor relative to a reference point to form a gap between the compressor and the heat exchanger; and placing a positioning device in the gap. The positioning device includes a lower sloped surface in slideable contact with the upper sloped surface of the transfer device. The method also includes the steps of: adjusting the positioning device so that the top surface of the positioning device contacts the compressor; and securing the positioning device to the heat exchanger and to the compressor.

Abstract: A method of controlling chiller capacity in a chiller system. The method comprises the steps of: measuring entering the fluid temperature of a fluid entering a heat exchanger; measuring the fluid temperature of the fluid leaving the heat exchanger; determining a desired leaving fluid temperature; establishing chiller capacity as a function of the difference between leaving fluid temperature and the desired leaving fluid temperature; and adjusting the determined chiller capacity as a function of the difference between entering fluid temperature and the desired leaving fluid temperature.

Abstract: A wire retainer for use in an air conditioning outdoor cabinet which houses a fan and a spine fin heat exchanger coil includes an extension portion, a base portion and a clip portion. The extension portion of the wire retainer is anchor-like and includes fluke-like members that, when inserted into and through spine fin material, lodge securely therein. The base portion of the retainer abuts the spine fin of the heat exchanger coil and positions the clip portion such that wires or a wire bundle running interior of the coil can be guided and secured appropriately so as not to be cut by the fan or buffeted and broken by the relatively high velocity, high volume stream of air that is drawn by the fan through the interior of the air conditioning cabinet and the heat exchanger coil housed therein.

Abstract: A refrigeration unit having a compressor includes a refrigerant gas inlet, a drive shaft, and at least one compression stage. At least one compression stage includes at least one impeller with a hub, the hub having a radially lobed bore. The drive shaft has a radially lobed portion complementary to the radially lobed bore of the impeller hub. The lobed portion of the drive shaft is received in the bore to define a coupling for transmitting torque from the drive shaft to the impeller. This coupling may have three lobes. The compressor may have more than one stage and more than one impeller. The first stage impeller is closer to the refrigerant gas inlet than the second stage impeller. The second stage impeller has a hub and radially lobed bore, wherein a second radially lobed portion of the drive shaft can be inserted to define another coupling. The cross-sectional area of this second coupling may be greater than the cross-sectional area of the first coupling.

Abstract: Oil cooling is accomplished in a refrigeration chiller by flowing hot oil into heat exchange contact with liquid refrigerant which is sourced from the chiller's condenser and returned thereto. The rejection of heat from the oil to the refrigerant in an oil-cooling heat exchanger causes vaporization of the refrigerant and, in turn, creates a density difference in the refrigerant flowing from the condenser and refrigerant in and downstream of the oil-cooling heat exchanger. This density difference is responsible for inducing and maintaining refrigerant flow through the heat exchanger for oil cooling purposes.

Abstract: An apparatus and method for using a programmable variable speed motor to indicate a clogged filter while providing a constant airflow acrcss a wide range of restrictions. A motor has speed and airflow parameters and a built-in constant airflow regulator. A blower unit is connected to the motor to draw air from the inlet to the outlet. A filter reduces airborne particles as air is forced from the inlet to the outlet by operation of the motor and blower. A control system adjusts the airflow parameter of the motor based on the motor speed and environmental conditions such as light and motion. If an electronic air cleaner filter is employed, a discharge counter counts the frequency of pops occurring across the electrodes of that filter. The control system adjusts the voltage across those electrodes based on the discharge counter values.

Abstract: A scroll compressor has a discharge check valve assembly comprised of a valve and a valve cage. The valve is maintained open within the assembly by the flow of discharge gas from the scroll set during the normal course of compressor operation and is essentially unaffected by momentary gas backflow and/or momentary pressure pulsations that can repetitively occur in the discharge pressure portion of the compressor shell during such operation. At the same time, the valve is quickly responsive to close the discharge port to gas backflow upon compressor shutdown. A dash pot volume, defined between the discharge valve and its cage, is vented to the discharge pressure portion of the compressor shell and is such that the valve is maintained open and does not chatter in the face of momentary gas backflow and/or pressure pulsations yet closes quickly when the compressor shuts down to prevent the backflow of high pressure gas to the scroll set.