Document 93Y93oNMxkV7bg8L5onLae33L

644 CHAPTER 36 '1948 Guiilr condensate and.the spray, provision must be made for overflow in summer, and replacement of water evaporated in winter. . -" - Dehumidifying Units: . . * In a further modification of spray type units,1 absorbent brine solutions such as lithium chloride are used'to remove moisture from the air: As explained in Chapter 38, the latent heat of the moisture removed- is changed to sensible heat,-so that coils must' be used as after coolers'to obtain the right dry-bulb temperatures. Factory produced units-arealso available for use with: Solid'adsorbents such as silica gel. These are also described in Chapter 38. Conditioner Remote Room Units For individual rooms, with cooling load requirements of 34 to 134 tons,, remote units are available in attractive casings for installation within the room. A suspended type' is shown in Fig. 3 and a floor type, such as is usually installed in place of an .existing radiator, is shown in Fig. 5. Furnished with chilled-water, from a central plant, these units offer a satisfactory method of conditioning existing offices, hotel, and apartment rooms. These units may be obtained with filters and outside air con nections, but for most satisfactory application are used as supplements to central systems that supply properly conditioned and filtered air to the areas served. Induction type units, using primary conditioned air under pressure to induce local circulation, are described in Chapter 43. Self-Contained Units ; A typical large self-contained unit is shown in Fig, 6. It is essentially a remote vertical type conditioner mounted on top of a sound insulated ,*Unit Air Conditioners Unit Air Coolers 645 enclosure containing the condensing unit. Air distribution is obtained by means of grilles mounted in the discharge plenum when the unit is located in the conditioned area. Duct distribution of conditioned air can be obtained by.removing the plenum connecting directly to the' blower dis charge, and safing the top of the unit. .. . The heat generated by-the compression of refrigerant gases and that given off by the electric motor is removed from the compressor compart ment in four ways: by the use of a water coil in the compressor compart ment; by utilizing the cold suction gases; by. drawing.part of the return air through the compressor compartment, find finally by circulating room air through the compressor compartment by meaps of a fan attached to the motor shaft. The. 734, 10, and. 15 ton self-contained units usually .have horizontal type conditioners.-' The condensing unit enclosures are riot completely sound insulated,' since they are-not'usually installed'in the conditioned area. Most units can be divided into two or three sections for ease of handling and installation. Although'most large self-contained units have water-cooled condensers, the 734, 10, and 15 ton units can be obtained for operation with evaporative-condensers. Self-Contained Room Cooling" Units Small self-contained units can be obtained with water-cooled conden sers but they are generally air cooled. The air-cooled types are small in capacity, ranging from 34 to 1J4 hp. Their, principal fipplicationis for conditiohing such spaces as hotel rooms, offices and residential living qufirters. A duct conriection between the unit and an outside window; or ventilated air shfift is required to permit disposal of the heat extracted from the conditioned area. The unit may stand in front of the window or be mounted on the window sill. Various styles and types of windows are encountered which increase the difficulty of making the window connections. The evaporation of condensate on the condenser coils, as a means of disposing of this moisture, tends to increase the condensing capacity and reduce the, operating head pressure. Some units add supplementary water so that increased capacity may be obtained from constantly wetted condenser coil surface. Connections to an electrical outlet may be by means of a conventional cord and plug or a permanent electrical connection, depending on local code rulings per-.. taining to the installation of small motors. The exterior finish of the unit in metal, wbod or-fabric is decorated to harmonize with office or bed room furnishings. A unit of the air-cooled condenser type for floor mounting is shown in Fig. 7. Of the two fans shown,, the lower one acts as condenser air fan, and in some units this fan is arranged with slirigers for discharging con densate on the condenser coil while the upper fan discharges air into the conditioned area. A feature of the design shown in Fig. 7 is that the condensate from the cooling coil is sprayed over the condenser surface and vaporized, thus eliminating the need for drain connections. A simple dampering arrangement is generally provided for exhausting some air from the room, in addition to introducing outside air and recirculating required amounts of air. It is possible to remove the equipment for winter storage or utilize the ventilating features for winter operation.