Abstract: Moulded articles of uniform wall thickness are prepared by vacuum-forming or thermoforming a composition comprising a uniform blend of, as base resin, a moulding grade resin having a continuous phase of a first copolymer of a styrenic monomer and an ethylenically unsaturated nitrile and a minor proportion of, as additive resin, a second copolymer of a styrenic monomer and an ethylenically unsaturated nitrile having an ultra high molecular weight, the forming operation being carried out at least 50.degree. C. above the glass transition temperature of the base resin and at a stress level of at most 1 MPa.

Abstract: Compositions comprising a carboxylated PPE resin and a polyamide having good compatibility and impact properties. The carboxylated PPE resin/polyamide alloys are produced by a process wherein a mixture consisting essentially of the PPE resin and a minor amount of an unsaturated carboxylic compound are first melt processed, then compounded with the polyamide.

Abstract: An environmental control system for controlling the environmental conditions in a swimming pool hall 1 comprises a heat pump having a multi-section evaporator 8, compressors 23a and 23b and a multi-section condensor 18.In the day-time, the dry bulb temperature in the pool hall is maintained by circulating space air through a duct 3 to the evaporator 8 where the latent heat is recovered from the moisture laden air. This heat is rejected via the condensor 18 either to the now drier recirculated air or fresh air from an inlet 13 or a mixture of air from the two sources. In a night mode of operation, circulation of space air through the duct 3 is prevented and instead it is recirculated via a direct recirculation duct 53 and is heated by the condensor 18, the heat used to do this being recovered from outside air inducted into the evaporator 8 via an inlet 50.

Abstract: An environmental control system has an evaporator section comprising an evaporator for extracting heat from (and dehumidifying) air destined for the controlled space or for exhaust--this air may be a controlled mixture of fresh and recycled air--and a chiller for extracting heat from a source such as well water and from a thermal store. The heat pump condenser section comprises a condenser for rejecting heat to air entering the space and a condenser receiver for rejecting heat to the store. The system includes a system controller (not shown) programmed to control operation in a manner tending to minimize the prime energy requirement.

Abstract: A variable air volume (VAV) system in which the inflow of outside air is maintained above a predetermined value by maintaining a substantially fixed negative pressure in the plenum by the use of a static pressure sensor and control system for controlling the speed of the return fan.

Abstract: A heat pump system in which the compressor speed is varied in response to load conditions by a programmed control system and the indoor coil fan speed, during heating operations, is proportioned to compressor speed as further modified by the outdoor air temperature.

Abstract: An adjustable surge and capacity control system for matching a capacity control system to an inverter-driven centrifugal compressor based liquid chiller having unknown surge characteristics. The necessary adaptation of the capacity control circuit to a particular chiller is attained by the provision of two potentiometers which are adjustable to develop a functional which avoids surge and operates the system in an efficient manner at all feasible operating point loads and heads. The use of a circuit employing a pair of potentiometers permits the formation of the appropriate functional with two degrees of shaping flexibility.

Abstract: A gas burner is provided with a shaped part at its upstream end for the admission of primary air and gas, the shaped part 24 being monolithic with the burner and having openings 34, 36 for the admission of primary air from above, and is downwardly open for admission of air from below, the part receiving a primary air shutter 52 which is generally cylindrical to fit in telescoping relation upon the burner end part 24, the shutter having a lower slot 56 to accommodate the seam 18 of the burner, and the shaped part having a downwardly open saddle 38 adapting the burner upstream end to be seated on a gas spud.

Abstract: A refrigerant condensing system for heating water includes a thermostatically-operated valve for delivering 140.degree. F. water from a condenser to the top of a water storage tank and a by-pass valve for allowing the heated water from the condenser, which is then heated to a lower temperature, to flow directly to the bottom of the storage tank after the upper third of the tank has been filled with 140.degree. F. water, thereby increasing the efficiency and heating capacity of the refrigeration system.

Abstract: A desuperheater control system for use in a refrigeration apparatus includes a thermostatic expansion valve which responds to the temperature and pressure at the outlet of a desuperheater for bypassing refrigerant flow from the condenser back to the suction side of the compressor. A pressure chamber is connected to the outlet of the expansion valve to sense the pressure therein. A water regulating valve is responsive to the pressure in the pressure chamber for regulating the water flow through the desuperheater so that the superheated refrigerant gas from the compressor is cooled to a pre-selected temperature having a minimum superheat.

Abstract: An evaporator inlet water temperature control system for controlling the inlet water temperature of an evaporator utilized in an inverter driven centrifugal chiller. The system creates the proper chilled water set point at the evaporator outlet needed to maintain the inlet water at its set point for greater efficiency of operation. Control is accomplished by generating an electrical error signal which is a function of an inlet water set point voltage and the actual inlet water temperature. A logic signal is produced as a function of the error signal detected by the circuit and establishes a dead zone band representing a range in which the error signal is acceptable. Output of the control system is passed to the capacity control circuit of an inverter driven centrifugal compressor chiller.

Abstract: A heat exchanger having a flow of air therethrough adapted for use in refrigeration systems includes a heat exchange coil and a plurality of sheet-like fins. The coil is formed of a plurality of tubes having a cooling medium flowing therethrough. Each of the fins are provided with openings for receiving the tubes in heat transfer relationship. A plurality of tabs are arranged in a surrounding relationship around the lower portion of the openings on the tubes for preventing the blow-off of condensate drops forming on the underneath side of the tubes.

Abstract: An adjustable surge and capacity control system for matching a capacity control system to an inverter-driven centrifugal compressor based liquid chiller having unknown surge characteristics. The necessary adaptation of the capacity control circuit to a particular chiller is attained by the provision of two potentiometers which are adjustable to develop a function which avoids surge and operates the system in an efficient manner at all feasible operating point loads and heads. The use of a circuit employing a pair of potentiometers permits the formation of the appropriate function with two degrees of shaping flexibility.

Abstract: An improved method of manufacturing a swash plate assembly for use in a compressor, fluid motor or similar device in which a plurality of pistons are connected, by means of connecting rods, to a swash plate which drives (or is driven by) the pistons. A plurality of piston assemblies are made by casting the piston body around one end of a connecting rod section which is formed with a ball, thus providing a ball-socket connection therebetween. Other connecting rod sections are cast-in-place and captured in sockets within the wobble plate. With the connecting rod being made in two pieces, the section connected to each of the pistons and the section connected to the swash plate are positioned in a fixed relation to one another in an appropriate fixture. The two sections of each connecting rod are then secured to each other, such as by welding, brazing or crimping, to complete the assembly.

Abstract: An apparatus and method for controlling continuously and discretely the speed of a heat pump compressor as a function of load conditions to run at least up to 150% of its rate-speed when operated in the heating mode to provide initial supplemental heating prior to turning on of electric heaters. The speed of the indoor condenser fan is maintained at its full rated-speed. The operation of the apparatus is controlled by a microprocessor with a program to provide improved performance and minimize energy consumption.

Abstract: An apparatus and method for controlling the sequential operation of supplemental electric heaters so that the amount of energy consumption is minimized. The operation of the heaters is prevented as long as a lower night set-back temperature can reach the higher reference set point during the daytime within a predetermined time interval. A microprocessor is provided to control the operation of night set-back automatically to affect a measured temperature of the conditioned space.

Abstract: A control system for a heat pump having at least one stage of supplemental heaters, said control system including an electronic thermostat capable of (1) sensing the rate of change of the temperature in the (indoor) conditioned space; and (2) bringing on supplemental heat, following temperature setup of the thermostat, only if the rate of temperature change is below some predetermined value. A suitable time delay can be built into the control to allow the heat pump to stabilize and therefore give a more realistic indication of the ability of the heat pump to handle a given load.

Abstract: An evaporator feed and control system maintains a relatively high level of stability over a wide range of varying loads. The evaporator system includes a first evaporator having a multiple pass inlet and a single pass outlet, and a second evaporator having an inlet and an outlet. The inlet of the second evaporator is connected to the output of the first evaporator. A control valve device is utilized for bypassing at least a portion of refrigerant-oil flowing in the first evaporator from the second evaporator directly to a suction line when system is operating at a reduced capacity.