Nagai Makoto

Bio: Nagai Makoto is an academic researcher from Hitachi. The author has contributed to research in topics: Heat exchanger & Air conditioning. The author has an hindex of 9, co-authored 51 publications receiving 355 citations.

Fin-tube type heat exchanger

Abstract: A fin-tube type heat exchanger has parallel heat transfer tubes and a stack of a plurality of plate fins mounted on the tubes. Heat exchange is conducted between a first fluid flowing through the tubes and a second fluid flowing through the stack across each of the fins. Each fin has flat tube-mounting portions spaced in the longitudinal direction of the fin and formed with tube-mounting holes and a louver section disposed between each adjacent pair of tube-mounting portions. The louver section has elongated slats extending longitudinally of the fin and having side edges each spaced from an adjacent side edge of an adjacent slat. The slats are classified into two groups in respect of the cross-sectional shape. The slats of one group have generally flat cross-sections to reduce the resistance of the fin to the flow of the second fluid through the stack and are disposed in planes offset from the plane of the tube-mounting portions. The slats of the other group have V-shaped or inverted V-shaped cross-sections to increase stiffness of the fin in the longitudinal direction thereof.

Impeller of centrifugal blower

Abstract: An impeller of a centrifugal blower includes a hub, a hub plate, a plurality of blades and a shroud. The hub plate has an outer diameter which is smaller than an inner diameter of the shroud and a portion of the blades existing in the difference between the diameters is provided with a parting plane of molds, whereby the impeller can be integrally molded by the injection molding.

Air conditioner and air conditioning method

Abstract: An air conditioner mounted on a vertical wall and an method, with the air conditioner including air intake ports and air exhaust ports provided on each side of and air conditioner body which contains heat exchangers, fans and motors. The air is drawn in from the sides of the air conditioner where it is heat-exchanged and then discharged from sides thereof.

Outdoor machine for air conditioner

Abstract: PROBLEM TO BE SOLVED: To make compact and silent an outdoor machine for an air conditioner which uses the air blowing-out surface of an axial fan installed to the upper section of an enclosure as its upper surface by providing a corner guide to at least one of the void sections in the corner sections formed of the front-face plate, roof plate, and one side-face plate which is adjacent to the front-face plate SOLUTION: A top-flow type outdoor machine 1 is provided with air supplying openings on its side-face sides and a heat exchanger 8 on its back side The machine 1 is also provided with a compressor 9, an accumulator 10, an axial fan, a bell mouth 12, etc, and a heat-exchanged wind exhausted front the fan 11 is discharged upward after passing through an exhaust pipe 7 and a guard net 16 In the machine 1, a corner guide 18a is provided to the void of each corner section formed of the front-face plate 2, side-face plate, roof plate 6, and bell mouth of the machine 1 Therefore, the outdoor machine 1 can be operated silently, because the heat-exchanged wind sucked from the heat exchanger 8 is prevented front staying in the voids of the corner sections and, at the same time, the efficiency deterioration of the fan 11 caused by uneven flows in the circumferential direction can be suppressed

Outdoor unit for air conditioner

Abstract: PROBLEM TO BE SOLVED: To decrease channel resistance by providing a motor supporting plate for supporting a fan comprising a supply/suction fan and a drive motor for fan between the bottom plate of a housing and the drive motor for fan thereby halving the area of the motor supporting plate when viewed from the front side of an outdoor unit SOLUTION: A motor supporting plate 1 comprises a pair of main plates 2a, 2b and an auxiliary plate 3 wherein the fixing legs 6 of a drive motor 5 for fan are supported by the main plates 2a, 2b, at the upper ends thereof, and fixed to a bottom plate 7 by means of an auxiliary plate 3 A heat exchanger 8 is disposed on the back face side of the bottom plate 7 The motor supporting plate 1 is placed between the drive motor 5 for fan and the bottom plate 7 and not placed between the drive motor 5 and a top plate 10 A specified space is thereby ensured at the upper half in the housing defined by the bottom plate 7, a front plate 9, the top plate 10, and the like, and channel resistance is decreased by halving the occupation area of the motor supporting plate 1 when viewed from the front side of an outdoor unit

Heat pump water heater

Abstract: A flash water heater using a heat pump includes a heat exchanger in which a refrigerant flow path exchanges heat with a water flow path. Tap water is led directly to the water flow path, and hot water supplied from the water flow path is used. The water heater includes at least one of the following elements: 1) a load setter for setting a heating amount in the heat exchanger, and a heating controller for regulating a heating amount in response to an amount set by the load setter; 2) a heater for heating water flowing through the water flow path in the heat exchanger and water flowing the path before and after the heat exchanger; 3) plural compressors; and 4) plural heat-pump cycles. The water heater is excellent in start-up of hot water temperature when the hot water supply starts, controllability, and efficiency.

Refrigerating cycle device

Abstract: A refrigerating cycle device using carbon dioxide as refrigerant capable of solving such a problem that when a receiver is installed against a low pressure, a cost and a volume are increased by a pressure resistant design to assure safety, wherein a first pressure reducing device (12) and a second pressure reducing device (15) are operated to vary the refrigerant pressure of a first heat exchanger (13) so as to regulate the refrigerant hold amount of the first heat exchanger, whereby since the unbalance of the amount of refrigerant between cooling and heating/dehumidifying can be reduced, the refrigerating cycle device can be efficiently operated with a downsized receiver or without installing the receiver.

Heat exchanger, and air conditioner

Abstract: In a heat exchanger for exchanging heat between a fluid, such as a refrigerant, and air, an object is to increase the surface areas of the fins while suppressing an increase in draft resistance, so as to attain the improvement of performance. To this end, corrugated sheet fins (70) are used as the fins of a heat exchanger (60). The fins (70) are shaped in corrugated form, and the direction of their edge lines is orthogonal to the leading edge and trailing edge. In the heat exchanger (60), a plurality of corrugated sheet fins (70) are disposed at a fixed pitch axially of heat transmission pipes (61).

Outdoor unit of air conditioner

Abstract: An air conditioner outdoor unit (1) comprises a case having a rectangular shape and composed of side panels (4, 4,--) in which a machine chamber (3) and a heat exchanger chamber (2) are defined so as to be vertically aligned, with the heat exchanger chamber disposed above the machine chamber (3) and sectioned by a partition plate (12) which also acts as a drain pan, the side panels surrounding the heat exchanger chamber are formed with air suctions ports (4a, 4a --). The outdoor unit (1) further comprises a heat exchanger unit (17, 18) having four side wall sections of which at least two opposing two sections are inclined inwardly by a predetermined angle with respect to inner surfaces of the side panels to which the air suction ports are formed. The outdoor unit case also contains a duct unit (20) arranged in association with the drain pan (12) for discharging drain and cooling an electrical part such as a heat sink (22).

Outdoor unit of air conditioner

Abstract: An outdoor unit of an air conditioner is provided. The outdoor unit includes a base assembly defining a lower exterior of the outdoor unit and supporting a plurality of parts, left and right panels that are provided on the base assembly to define left and right exteriors of the outdoor unit, a pair of top panels that are provided between upper ends of the left and right panels to define a top exterior of the outdoor unit, a blower assembly including a blower fan generating air current and a motor providing a torque to the blower fan, a frame assembly supporting the blower assembly and including a pair of transverse supports interconnecting the left and right panels and a motor mount disposed between the pair of transverse supports to support the motor, and a shroud enclosing the blower fan and the motor and guiding airflow generated by the blower fan. The motor mount is received to an inside of the shroud.