FR2493972A1 - METHOD FOR DEFROSTING HEAT PUMP AIR PROCESSING APPARATUS AND DEVICE FOR PERFORMING THE PROCESS - Google Patents

Abstract

THE INVENTION CONCERNS A PROCESS AND A DEVICE FOR IMPROVING THE DEGRIVING OF EVAPORATORS 4 AND OF DRAINING BINS 12 IN AIR TREATMENT APPLIANCES USING HEAT PUMPS. THE INVENTION USES TWO HEAT PUMP DEVICES, IN WHICH THE EXHAUST AIR IS CONDUCTED ALONG THE LOWER SIDE OF THE DRAINING BINS 12 AND, THROUGH A SHAFT 13, TO AN EVAPORATOR 4 OR TO BOTH, THE EVAPORATORS 4 BEING ARRANGED ABOVE THE DRAINAGE BINS 12 AND SPACED THEREOF. THE INVENTION IS APPLICABLE TO THE SUPPLEMENTARY HEATING OR TO THE REFRIGERATION OF BUILDINGS WITH DEFROST AND OBTAINING AN IMPROVED EFFICIENCY AND A BETTER AVERAGE ANNUAL HEAT FACTOR.

Description

The present invention relates generally and essentially to

  A method of improving the defrosting of evaporators and drain or drain trays or cuvettes in heat pump air handling apparatus and an improved apparatus

  for the execution of this procedure and the various

  cations and uses resulting from their implementation and the systems, assemblies, equipment, arrangements,

  equipment and installations provided with such devices.

  Thermal energy is contained in the coldest atmospheric air. By means of a heat pump, this heat is used or exploited and is applied, among other things, to the reheating of fresh air supplied to buildings. Heat pumps can then also be used for the recovery of heat on the outgoing air, evacuation evoked. The system may consist of two separate circuits, one of which takes or draws its heat from the exhausted air while the other receives its heat from the atmospheric air. For example, heat pumps can heat buildings or buildings up to an outside temperature of -51C before heat or heat input.

extra bed is necessary.

  The advantages of heat pumps are, in a known manner, that more heat is obtained than what corresponds to the effect brought, that is to say that the factor or heat coefficient is greater than 1. In In addition, the capital invested is better used, especially in cases where the system is switchable or reversible and

  applicable to cooling or refrigeration in summer.

  In known recovery systems with heat pumps or heat pumps for cooling, which are in operation during low ambient temperatures, problems currently lie in the fact that evaporators and drain trays or basins must be kept free of ice layers. or frost in such a way that reliability or safety of

  Optimum operation and performance are achieved.

  Melting or melting water is formed during defrosting and this is why the evaporators are placed in drainage bins for collecting and discharging water. During repeated defrosting of evaporators that are placed in a drain pan for a long time during low outdoor temperatures, the lower part of the evaporator and drain pan is not fully defrosted and / or not completely emptied of meltwater before the defrosting period is over When a repeated defrosting occurs, a new layer of ice or frost is formed after each defrosting period until a gradual compact ice block in the drain pan and at the

  lower part of the evaporator.

  This block of ice adversely influences the operating efficiency of the evaporator and, consequently, of

  the entire installation. The tubular system of evapo-

  The controller is often subdivided into several separate piping circuits, which are

  respectively supplied with cooling agent or fluid

  and from a distributor or nurse device or the like which provides each circuit with an equal amount of coolant. During the formation of ice or frost, the heat transfer, on the air side in the frosted part of the evaporator, becomes very bad, which negatively influences the evaporation of the refrigerant in the tubular circuit or of

  piping that is located in this part of the evaporator.

  The dewatering valve connected to the evaporator is, under these conditions, controlled by the reduced refrigerant vaporization in this frost-influenced circuit, so that the supply of cooling fluid to the entire evaporator is reduced, which appreciably decreases the capacity or the heat absorption capacity of the evaporator and, consequently, the operating efficiency and the

aforementioned heat factor.

  The object of the present invention is to eliminate the inconveniences

  above mentioned and to create a simple and safe or reliable process and a heat pump installation for carrying out the process by obtaining a heat factor

average annual high.

  This is achieved in an air handler at

  at least two heat pumps with respectively one compressor

  a condenser, valve or expansion valve, evaparator and drain pan, according to the method according to the invention in that exhaust air of a unit heated by the air-treatment apparatus, is constantly driven, by means of an exhaust air blower, to the lower side of all the drainage tanks and then upwards between the drainage tanks between which a shutter or the like is arranged, whereas by adjusting this flap, the exhaust air is guided either through one or the other or two or more evaporators which is or are thus de-iced, these evaporators being arranged at a height teII above drainage bins they are not in contact

direct with these.

  According to another characteristic of the invention, the compressor is stopped while the associated evaporator is

  defrosted by exhaust air.

  According to yet another characteristic of the invention, the compressors and / or the liquid separators and / or the condensing or melting water containers and pipes are also arranged in the air flow passage.

  hot exhaust before the evaporators.

  According to another characteristic of the inrEntion,

  drainage tanks, below the evaporators, are con-

  bathed, on their lower side, with air of

  with the aid of exhaust air blowers while the evaporators, placed above the tanks, are intermittently defrosted as required. The invention also relates to a device for carrying out the aforementioned method, dutype to air handling unit with two or more compressor heat pumps, condenser, vane

  or expansion valve, evaporator and drain pan.

  In accordance with the invention, this device comprises a duct for supplying exhaust air to the lower side of the drainage tanks and a flap between the tanks for diverting exhaust air between the evaporators and a horizontal or slightly inclined evaporator placed at a certain distaaoe

above the drainage bins.

  The installation according to the invention is advantageously carried out with at least two coated evaporators which have no direct contact with the drainage tanks. The drains are arranged in such a way that the air leaving the installation passes along the lower side of the tanks, which prevents the undesirable formation of frost or ice in the tanks, without additional or auxiliary heaters. bins, as for example

  electric heating elements are necessary.

  The exhaust air then flows between the drains and through a valve or flapper valve that controls or adjusts the outgoing air stream to the evaporator or selected evaporators. The outgoing air stream can be used partly as a sole source of heat or partly together with outside air introduced as a mixture. The outgoing air is usable, * ar oetyEncemEnt, also as a heat source for the

  defrosting a frosted or ice-covered evaporator

  above the drain pan. Compressors and other exothermic or heat generating components are preferably disposed in the exhaust air stream.

  before the drains and evaporators.

  During the defrosting of an evaporator, its blower and compressor are stopped, the liquid refrigerant fluid of the evaporator being evacuated by the so-called "dump-down-s-bp" effect or suction or drain stop The warm or lukewarm exhaust air then flows through the ice-covered evaporator, in which case the ice melts and the meltwater or melt water drips into the drain pan whose conduct The condensate drain is in the hot or warm exhaust air stream and is connected to a frost-free vent within the building or surrounding building. transferring the condensate drain from the drain pan prevents the formation of ice in the pipe, which could previously partly cause flooding and in part some other ice or frost formation

in the drain pan.

  Defrosting by venting according to the invention means that this must not be produced by the hot gas from the compressor, so that no reversing valve or reversibility valve, which switches between the evaporator and condenser , is not necessary. A battery, placed in the building, then absorbs no heat, which otherwise would have to be compensated for by the additional heat of electric heating or alarm. Furthermore, no energy is supplied to the compressor as long as it is

  stopped during the defrost period.

  This way of using the outgoing air or evacuation

  result in a reliable de-icing method and at the same time an increase in

  average annual calorific factor.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will appear more clearly on reading the description

  explanatory which will follow with reference to the accompanying schematic drawings given solely by way of non-limiting example illustrating a specific embodiment currently preferred with two compressors, condensers and evaporators which are connected, in a manner not shown,

  between them and to a valve or expansion valve not shown

  sent through the necessary pipes or pipes. In the drawings: FIG. 1 represents the constitution or the basic assembly of a heat pump installation; - Figure 2 is a sectional view through an air treatment device according to the invention; and - Figure 3 is a vertical sectional view through the air treatment device according to Figure 2,

in the vicinity of the evaporator.

  A heat pump comprises, as shown in Figure 1, in principle a compressor 1 in which a gaseous refrigerant is compressed, so that its temperature crott. The fluid is brought to a condenser 2

  located in a space or room to be heated or the like.

  The air of the room is heated and the coolant is cooled in the evaporator 2, after which the refrigerant is returned and then passes through a valve or expansion valve 3. In it, the pressure is lowered and the temperature decreases and the refrigerant is then brought to an evaporator 4. This evaporator is supplied for example with atmospheric air or exhaust air from the aforementioned room or space. The air warms the cold refrigerant, after which it is returned to the compressor 1 and the operating process is repeated. Since the outside air and the exhaust air contain a certain amount of moisture, frost formation previously mentioned on the evaporator often occurs at low outdoor temperatures. Figure 2 shows a section through the air handler which makes use of the idea of the invention. The right-hand part in FIG. 2 shows here a known technique with two condensers 2 and a posterior heating device 5 mounted downstream. The latter may for example be an electric battery and possibly provide a necessary supplemental heat supply if the condenser heat was not sufficient to bring the fresh air to the temperature displayed on a sensor or room thermostat or on a fresh air sensor. Before the condenser 2 are the filter 6 for the outside air and the exhaust air as well as flaps, flaps, butterflies or

  mixing adjustment registers 7.

  Outgoing air is blown into the air handler using an exhaust air blower 8. The outgoing air flow partially flows to the right in the figure 2 through the flaps or butterfly valves 7, through the filter 6, the condenser 2 and the rear heater 5 to achieve a fan blowing fresh air 9 which brings the treated air to the room in question. All this is known. The remaining part of the exhaust air is led to the left in FIG. 2, passes through flaps or outgoing air butterfly dampers 10 and

  flows along the compressors 1 while bathing it, the-

  which are cooled, and possibly along a liquid separator which is indicated schematically at 11, after which the warm or hot exhaust air, which is heated more by the heat of the compressor, is guided along the part The bottom of two drainage tanks 12. These are heated, in which case ice, possibly previously formed, is melted and the melt water is evacuated by flowing through a conduit not shown, also placed in lecouxmrt

  hot air coming out and leading to proper evacuation.

  As best shown in FIG. 3, the outgoing air flows upwards between the drainage tanks 12 to another flap 13 and is brought to one or

  to the other of the two evaporators4 or to the two evaporators 4.

  If the outgoing air flow rate is sufficiently large, no outside air is used as a heat source for the right evaporator as shown in Fig. 3 and the outgoing air shutter is located in the position shown in continuous solid lines in the figure of the drawing. The associated heat pump blower 14 is not in use or in action. The left evaporator 4 receives its heat exclusively from the outside air and the associated heat pump fan 14 is in use or in action. The left evaporator 4 can thus be exposed to icing or ice formation while the right evaporator 4, if it was previously connected to cold outside air, can be the object of the defrost by the arrangement shown

system.

  The installation, shown in FIG. 2, can also be used as a refrigeration device during the hot season. By means of, for example, a four-way valve, the condensers are then conmuted to serve as evaporators while the evaporators are switched to As condensers, the condenser blowers are in operation and are controlled by the condensing temperature. The OR

  the evaporators cool a mixture of exhaust air

  and outside air or outside air only to a temperature that is set by a room sensor or thermostat or by a fresh air temperature sensor.

Claims (6)

R E V E N D I C A T I 0 N S   1.- Method for improving the evaporation defrosting   and at least two heat pumps, with respectively a compressor, a condenser, a valve or expansion valve, an evaporator and a drain pan, characterized in that the exhaust air of a unit heated by the air handling unit is constantly conducted, with the aid of a blower of exhaust air, along the lower side of all the drainage tanks (12) and then upwards between the drainage tanks, in that a flap (13) is arranged between the drainage tanks, in that, by the adjustment of this flap, the exhaust air is guided either through one or the other or two or more evaporators (4) which is or are thus de-iced, and in that the evaporators (4) are arranged at one or more of the two 'they   are not in direct contact with them.   2. A method according to claim 1, characterized in that the compressor (1) is stopped while the associated evaporator (4) is defrosted by exhaust air. 3. A process according to claim 1 or 2, characterized in that the compressors (1) and / or the liquid separators (11) and / or the condensation and melting water containers and pipes are also arranged in the air flow passage   hot exhaust before the evaporators (4).   4. Process according to at least one of the claims   previous, characterized in that the drainage tanks (12) below the evaporators (4) are constantly bathed on their lower side, by exhaust air using exhaust air blowers while the evaporators, placed above them,   are defrosted intermittently as needed.   5.- Device for carrying out the process according to   least one of the preceding claims, from type to   air handling apparatus with two or more compressor heat pumps, condenser, valve or expansion valve, evaporator and drain pan, characterized by an exhaust air supply duct on the lower side of the drain trays (12), by a flap (13) between the bins for the evacuation air deflection between the evaporators (4) and by a horizontal or slightly inclined evaporator (4) placed at a certain distance above the drainage bins.   6.- Device according to claim 5, characterized in that the compressors (1) are placed before the evaporators (4) in the air flow passage discharge.