GB2144212A

GB2144212A - Apparatus for conditioning room air

Info

Publication number: GB2144212A
Application number: GB08320672A
Authority: GB
Inventors: Martin Keller
Original assignee: Sulzer AG; Gebrueder Sulzer AG
Current assignee: Sulzer AG
Priority date: 1981-09-30
Filing date: 1983-08-01
Publication date: 1985-02-27
Also published as: GB8320672D0; GB2144212B; DE3322075C2; FR2548334A1; DE3322075A1; CH654901A5

Abstract

Apparatus for conditioning room air has an induction duct (22) supplied with primary air by way of a nozzle-like induction element (26) near its bottom end, an induced flow, in the form of a mixture of primary air and of room air drawn in through an inlet near the floor, forming in the induction duct (22), such mixture being able to issue into the room through a grill-like outlet (24) near the top edge of the apparatus. A heating element (12) is provided to heat the mixed flow in the induction duct (22). A primary air branch duct (34) is disposed adjacent the induction duct (22); a changeover flap (48) directs the primary air into the induction duct (22) or into the branch duct (34) or into both. Air entering the branch duct (34) discharges into the room through a nozzle-like discharge element (36) so devised that the primary air is delivered (62) to the room at a substantially higher velocity than the exit velocity of the induced mixed flow (58). <IMAGE>

Description

SPECIFICATION Apparatus for conditioning room air This invention relates to apparatus connectable to a primary air supply duct to condition the air in a room, the apparatus having an induction duct adapted to be supplied with primary air by at least one induction element near its bottom end; a room air entry which is near the duct bottom end and through which room air is, with the apparatus in operation, drawn in by the induction effect of the primary air issuing from the induction element into the duct, the duct extending upwards to an induction duct outlet for mixed primary air and room air; and a heating element having heat exchange surfaces on which the mixture of primary air and room air is incident.

An apparatus of this kind has been described, for example, in the journal "Heizung/Lüftung/Klima- technik-Haustechnik" 29 (1978), No. 11, page 425, Figure 7. This known apparatus is supplied through a single-duct system with fresh air as primary air which may, if required, have been given appropriate processing in a central station and whose temperature is always a few degrees Celsius below the average required room temperature. A disadvantage of this known apparatus is that the air and temperature distribution in the room is unsatisfactory in summer operating conditions, and even in winter when the heating element is not required to deliver heat.Since the primary air temperature is below the room air temperature, the convection flow which normally carries the primary air into the room together with the induced room air flow is inoperative when the heating element is not heating. Since there is a considerable loss of kinetic energy in the cold primary air flow as a result of producing an induction flow, the cold primary air drops to the ground immediately after issuing from the apparatus and fills up the bottom of the room, producing a "pool" of cold air and impairing the fresh air and temperature distribution. It is an object of the invention to substantially obviate these disadvantages.

According to the present invention apparatus connectable to a primary air supply duct to condition the air in the room has: an induction duct adapted to be supplied with primary air by at least one induction element near its bottom end; a room air entry which is near the duct bottom end and through which room air is,with the apparatus in operation, drawn in by the induction effect of the primary air issuing from the induction element into the duct, the duct extending upwards to an induction duct outlet for mixed primary air and room air; a heating element having heat exchange surfaces on which the mixture of primary air and room air is incident; a primary air branch duct devoid of heating elements leading upwards to at least one outlet nozzle; and valve means for directing the primary air either into the induction duct or into the branch duct or into both ducts; the construction being such that when primary air is directed solely into the branch duct the primary air issues from the or each outlet nozzle at a substantially higher velocity than the mixed primary air and room air issues from the induction duct outlet when primary air is directed solely into the induction duct.

An effect of apparatus constructed according to the invention is that the air flowing through the primary air branch duct and bypassing the induction duct acquires such a velocity in its passage through the outlet nozzle or nozzles as to be delivered into the room with a considerable penetration depth. Consequently, cold air does not drop to form the "pool" of cold air very near the apparatus. The primary air gradually loses its energy as it mixes with the room air and fresh air is distributed substantially homogeneously in the room, with a correspondingly advantageous temperature distribution.

The specification of German utility model 1 931 669 describes an arrangement having two ducts separated by a partition, one duct having a heating element whose upright heat exchange strips occupy the entire duct cross-section over some of the duct height. The second duct is disposed directly above an intake duct for primary air which can issue through nozzle-like expansion elements. By means of a flap the primary air can be guided either laterally into the duct having the heating element or directly into the second duct.

In both of the two operative positions of the flap primary air first issues into a chamber at the bottom end of both ducts, such chamber being in permanent communication with the room air by way of an aperture near the floor. Consequently, the issuing primary air produces an induction flow in any position of the flap and each of the two ducts conveys a mixture of primary air and room air to the grill-like mixture outlets near the top edge of the apparatus.

In this known form of apparatus the induction effect retards the primary air flow considerably. No appreciable acceleration occurs at the issue of the mixture from the apparatus, so that this known construction suffers from the disadvantages described.

In an apparatus which is constructed to be mounted on a wall or at a window will, the or each outlet nozzle may be constructed to direct issuing air obliquely upwards and inwards towards the room interior. This prevents a diversion of the air flow along the wall because of the Coanda effect.

Preferably, the apparatus is so constructed that with the valve means set to direct primary air solely into the branch duct or solely into the induction air, the rate of flow of primary air is substantially the same. In this way, the valve means can be operated exactly as required to suit the climatic conditions in the particular room concerned without causing variations in the quantity of infed primary air; any such alteration might impair distribution within the primary air system.

The heating element can be a panel-like heating wall at least partly bounding the induction duct on the room side. With this arrangement, even when the primary air supply is inoperative but when the heating element is in operation, there can be a convection flow to cover heat demand, heat also being yielded by radiation.

Preferably, the or each outlet nozzle is dimensioned to give a primary air exit velocity from the branch duct into the room of at least 4 miser. This ensures satisfactory and thorough mixing even at relatively great room depths.

The invention may be carried into practice in various ways but one form of apparatus embodying the invention will now be described by way of example with reference to the accompanying drawing, the singie Figure of which is a vertical cross-section through the apparatus.

A heating wall 14 is located adjacent a window sill 10. The heating wall is connected to flow and return pipes 16, 18 mounted on a bracket 20 and carries fins 12 which project into a vertical induction duct 22; a linear lattice or grill 24 is disposed at the top end of the duct 22 and at the bottom thereof there is a nozzle-like induction element 26 and a secondary air inlet 28 for room air induction.

Extending parallel to the duct 22 is a primary air branch duct 34 which has in its top part a nozzlelike discharge element 36, in the form of a gap, which is inclined obliquely upwards and inwards towards the room interior. The branch duct communicates in its bottom part via an aperture 38 with a primary air supply duct 40 to which air is delivered by a feed line 42 past a throttle or restrictor flap 46 secured to an adjusting screw 44. A valve means afforded by a pivoted changeover flap or damper 48 is disposed in the duct 34.

It will be assumed for the purposes of a first example of how the system described operates - i.e., pure winter operation - that the flap 48 is in the top position shown. In this event the primary air flows, as indicated by arrows 50, 52, 54, into the induction duct 22, and the room air drawn in by induction at floor level flows, as indicated by an arrow 56, through the secondary air inlet 28 into the induction duct 22. The mixture of primary air and secondary air flows over the heating surfaces 12 of the heating element 14 and leaves the duct in a heated state, as indicated by an arrow 58, through the grill 24.

It will be assumed for a second example of how the system operates - i.e., summer operation that the flap 48 is in its bottom position shown in chain lines. The heating wall 14 is inoperative and, therefore, cold. In this case the primary air infed in the direction indicated by an arrow 52 flows through the branch duct 34 as indicated by an arrow 60 and issues from the nozzle-like discharge element 36, as indicated by an arrow 62, at an inclination such that the flow in the direction of the arrow 62 produces optimum air guidance as far as the opposite wall of the room.

For a third example of how the system operates - i.e., mixed operation - it will be assumed that the flap 48 is in its central position shown in dashed lines. In this case the primary air inflowing as indicated by the arrow 52 is divided between the induction duct 22 and the branch duct 34 as indicated by respective arrows 54, 60; the air flowing through the induction duct 22 in the direction indicated by the arrow 54 also mixes with the room air taken in in the direction indicated by the arrow 56. The mixture ratio as between heated 7 primary air and unheated primary air can be varied as required by appropriate adjustment of the flap 48.

The invention is not limited to the embodiments shown; more particularly the nozzle-like induction element 26 and the nozzle-like discharge element 36 could each take the form of a subdivided slot or of discrete nozzles disposed in one or more rows.

Control or adjusting elements other than the restrictor or throttle flap 46, such as interchangeable aperture plates, could be used at the entry of the primary air into the duct 40. A heating element disposed entirely within the duct 22 could be used instead of the heating wall 12. The primary air can be processed in any required manner; however, the apparatus can operate on unprocessed fresh air derived from the ambient air.

Claims

1. Apparatus connectable to a primary air supply duct to condition the air in a room, the apparatus having: an induction duct adapted to be supplied with primary air by at least one induction element near its bottom end; a room air entry which is near the duct bottom end and through which room air is, with the apparatus in operation, drawn in by the induction effect of the primary air issuing from the induction element into the duct, the duct extending upwards to an induction duct outlet for mixed primary air and room air; a heating element having heat exchange surfaces on which the mixture of primary air and room air is incident; a primary air branch duct devoid of heating elements leading upwards to at least one outlet nozzle; and valve means for directing the primary air either into the induction duct or into the branch duct or into both ducts; the construction being such that when primary air is directed solely into the branch duct the primary air issues from the or each outlet nozzle at a substantially higher velocity than the mixed primary air and room air issues from the induction duct outlet when primary air is directed solely into the induction duct.

2. Apparatus as claimed in Claim 1 in which the valve means comprises a single damper.

3. Apparatus as claimed in Claim 1 or Claim 2 which is constructed to be mounted on a wail or at a window sill and in which the or each outlet nozzle is constructed to direct issuing air obliquely upwards and inwards towards the room interior.

4. Apparatus as claimed in Claim 1 or Claim 2 or Claim 3 which is so constructed that with the valve means set to direct primary air solely into the branch duct or solely into the induction air, the rate of flow of primary air is substantially the same.

5. Apparatus as claimed in any of the preceding claims in which the heating element is a panel-like heating wall and at least partly bounds the induction duct on the room side.

6. Apparatus as claimed in any of the preceding claims in which the or each outlet nozzle is dimensioned to give a primary air exit velocity from the branch duct into the room of at least 4m/sec.

7. Apparatus connectable to a primary air supply duct to condition the air in a room, constructed substantially as described herein with reference to the accompanying drawing.

8. Apparatus as claimed in any of the preceding claims installed in a room with the induction duct and the branch duct connected to a primary air supply duct.