EP0826934B1 - Method for controlling the charging and decharging of electric storage heaters - Google Patents

Abstract

During discharge, heat transfer rate depends on fan speed, controlled by altering the fan motor voltage. A thermostat monitoring the ambient temperature cuts the fan(s) out at the applied setting (Tc), and in at a slightly lower value (Tl). As temperature recovers (AB), fan motor voltage is raised from 170 in 3x20v steps, each lasting 5 minutes, the final step being extended if necessary to achieve the set level (Tc). If the tariff so provides, a continued fall (AE) to a lower temperature (T2), above the overnight setting (T3), is countered by partial re-energising of the heater elements. Each night's charge is determined according to the percentage charge remaining the previous evening, as calculated from fan running times and speeds.

Description

The present invention relates to electric heaters with accumulation, commonly referred to as "accumulators", as well as similar heating systems and aims for better control as well phases of heat accumulation or charging of such devices as phases of restoring the stored heat.

This type of device briefly consists of a stack of bricks refractory, armored electrical resistances housed in the stack, air circulation channels through the stack and a turbine system forcing air taken outside into the channels and then rejecting it at the exterior and command / control means, on the one hand, of the resistors electrical and, on the other hand, turbines, depending on various parameters.

These devices are well suited to energy pricing methods electric at successive tariff periods during a 24 hour cycle.

Generally the load of the stacking of bricks or core is carried out at night during so-called off-peak or reduced tariff hours and the heat accumulated at night is returned during the day as needed of the room where the appliance is installed, these needs being displayed by the user from various systems such as room thermostat, control switch, regulator, etc.

An accumulator is generally charged according to the temperature outside the room to be heated.

However, it happens quite frequently, especially in the off-season, that one night with a touch of cold be followed by a relatively mild day. he it follows that the core of the accumulator will charge beyond what will be necessary to meet the needs demanded during the day, due to the relatively mild outside temperature.

Known systems for regulating the charge / discharge of accumulators are not satisfactory in such periods of high thermal amplitude between night and day.

The present invention specifically aims to provide a improved regulation allowing both better user comfort and more economical management of the energy consumed.

A/ en ce qui concerne la décharge ou restitution :

• à déclencher la mise en service d'au moins une turbine lorsque la température mesurée dans le local où se trouve l'appareil descend en dessous d'un premier seuil pré-déterminé par rapport à la température de consigne affichée et en deçà de celle-ci,
• à moduler, à chaque mise en service de la ou des turbines, leur vitesse de rotation suivant les phases successives ci-après :

  v1 :

  vitesse nominale, pendant une durée prédéterminée ;

  v2 :

  vitesse réduite à un premier niveau pendant une durée prédéterminée,

  v3 :

  vitesse amenée à un deuxième niveau supérieur au premier, pendant une durée prédéterminée,

  v4 :

  vitesse amenée à un troisième niveau intermédiaire entre la vitesse nominale et le deuxième niveau, pendant une durée prédéterminée ;

• - le passage de l'un des régimes v2 et v3 au régime suivant n'étant effectué que si les deux conditions suivantes sont remplies :
• 1) la température du local est inférieure à celle de consigne ;
• 2) l'élévation de température dans le local pendant la durée de la phase qui vient de s'achever est inférieure à un seuil prédéterminé ;
• - chaque phase v2, v3, v4 étant, si ladite élévation de température, à la fin de la phase considérée, est supérieure audit seuil, recommencée dans les mêmes conditions, un nombre déterminé de fois ;
• - et l'arrêt des turbines étant commandé à tout moment dès que la température du local atteint ladite valeur de consigne affichée ;

B/ en ce qui concerne la charge du noyau :

1) pendant les heures de tarification réduite :

a) à cumuler sur 24 heures et en dehors desdites heures de tarification réduite, les temps de fonctionnement des turbines en pondérant ces temps en fonction de la vitesse des turbines dans chaque période de fonctionnement ;

b) et, en fonction d'un abaque de pourcentage de charge en fonction du total ainsi cumulé des temps de fonctionnement des turbines, à déterminer un pourcentage de charge du noyau et à limiter la charge du lendemain dudit noyau à ce pourcentage ;

2) pendant les heures de restitution :

a) à effectuer une relance :

• si, à la fin de la succession desdites phases v1 à v4, l'élévation de la température du local pendant le temps cumulé de fonctionnement des turbines est inférieure à un seuil prédéterminé ,
• ou si la température dudit local atteint en descendant un deuxième seuil prédéterminé par rapport à la température de consigne, en deçà dudit premier seuil,

b) et à arrêter la relance dès que la température du local atteint ladite valeur de consigne.

To this end, the subject of the invention is a method of regulating the charge and discharge of electric storage heaters or the like and in particular of the type comprising a core formed of refractory bricks, electrical resistors for heating the core , and a plurality of forced air circulation turbines to be heated in core channels, method comprising

A / regarding the discharge or return:

• to trigger the commissioning of at least one turbine when the temperature measured in the room where the device is located drops below a first predetermined threshold relative to the displayed set temperature and below it this,
• to modulate, at each commissioning of the turbine (s), their speed of rotation according to the successive phases below:

  v1:

  nominal speed, for a predetermined duration;

  v2:

  speed reduced to a first level for a predetermined duration,

  v3:

  speed brought to a second level higher than the first, for a predetermined duration,

  v4:

  speed brought to a third intermediate level between the nominal speed and the second level, for a predetermined duration;

• - the transition from one of the v2 and v3 regimes to the next regime being carried out only if the following two conditions are met:
• 1) the room temperature is lower than the set temperature;
• 2) the temperature rise in the room for the duration of the phase which has just ended is less than a predetermined threshold;
• each phase v2, v3, v4 being, if said temperature rise, at the end of the phase considered, is greater than said threshold, restarted under the same conditions, a determined number of times;
• - and the turbine shutdown being controlled at any time as soon as the room temperature reaches said displayed setpoint;

B / with regard to the charge of the nucleus:

1) during reduced pricing hours:

a) to accumulate over 24 hours and outside said hours of reduced pricing, the operating times of the turbines by weighting these times as a function of the speed of the turbines in each operating period;

b) and, as a function of a load percentage chart based on the total thus accumulated of the operating times of the turbines, to determine a percentage of core load and to limit the load of the day after said core to this percentage;

2) during return hours:

a) to raise:

• if, at the end of the succession of said phases v1 to v4, the rise in the temperature of the room during the cumulative operating time of the turbines is less than a predetermined threshold,
• or if the temperature of said room reaches by descending a second predetermined threshold with respect to the set temperature, below said first threshold,

b) and to stop the restart as soon as the room temperature reaches said set value.

According to a variant implementation of the invention, the relaunch possible charge of the nucleus during the restitution period is preferably carried out at one third or two thirds of the power of the device.

According to another variant of implementation of the invention, for a operation at reduced speed, a micro-controller is sent to the device a signal prohibiting the commissioning of the return turbines, unless the room temperature drops below a third threshold by relative to the set temperature, below the second threshold, the charge modes of the nucleus remaining unchanged.

Advantageously, this other variant is implemented using a multi-position switch: STOP-FREEZE-REDUCED-COMFORT, known type, with a single pilot wire connected to the micro-controller of the device, the REDUCED position having the effect of lowering the set values and therefore to introduce said third threshold below which the restitution of the nucleus will be ordered.

In the present description, the term "device" means only one accumulator or several supplied in parallel, these being able to be themselves used concurrently or in relay with heaters other types, for example convectors, radiant panels, etc.

• Figure 1 représente un diagramme de fonctionnement de la restitution de la chaleur stockée dans un accumulateur, conformément au procédé de l'invention ;
• Figure 2 représente un diagramme des vitesses des turbines selon le procédé de l'invention ;
• Figure 3 représente un abaque du pourcentage de charge du noyau de l'accumulateur en fonction des temps cumulés de fonctionnement des turbines, conformément au procédé de l'invention, et
• Figure 4 est un schéma d'une installation comportant plusieurs types d'appareils de chauffage électrique dont un accumulateur, pilotés à partir d'un commutateur à fil pilote unique.

Other characteristics and advantages will emerge from the description which follows of an embodiment of the method of the invention, description given by way of example only and with reference to the appended drawings in which:

• Figure 1 shows an operating diagram of the return of the heat stored in an accumulator, according to the method of the invention;
• 2 shows a diagram of the speeds of the turbines according to the method of the invention;
• FIG. 3 represents an abacus of the percentage charge of the core of the accumulator as a function of the accumulated operating times of the turbines, in accordance with the method of the invention, and
• Figure 4 is a diagram of an installation comprising several types of electric heating apparatus including an accumulator, controlled from a single pilot wire switch.

Figures 1 and 2 illustrate the principle of heat recovery stored in the core of an accumulator, according to the process of the invention.

The charge of the core takes place overnight during the pricing period reduced and the return of the stored heat takes place the following day during the normal pricing period known as peak hours following immediately said reduced pricing period, the cycle charge / return spanning 24 hours. However, exceptionally restitution cycles may be required to maintain temperature ambient overnight.

In accordance with the invention, a first temperature threshold T ₁ will be defined, below the reference temperature Tc displayed by the user of the room where the accumulator is installed, for example on a room thermostat incorporated in the 'accumulator or fixed remotely (wall sensor). The threshold T ₁ is fixed relative to the setpoint Tc, which is for example 20 ° C. In the example illustrated in Figure 1, the threshold T ₁ is 0.5 ° C below Tac.

According to the method of the invention, we will constrain, outside the so-called off-peak period, the ambient temperature of the room to remain at inside the range 19 °, 5 C - 20 ° C by a specific regulation of the dynamic restitution, that is to say the control of the turbines of the accumulator.

In Ta in FIG. 1, the curve of evolution of said ambient temperature is shown, which is going down. On reaching (point A) the threshold T ₁ , it will trigger a process of putting the turbines into operation, for a period of time t, until the ambient temperature Ta ₁ has reached the set temperature Tc ( point B).

During the time period t, we will drive the turbines of the accumulator according to the diagram in FIG. 2 illustrating the regime of fan speeds during the time period t.

At startup, for example during the first 5 seconds (td) of the period t, the turbines are launched at their nominal speed v1 supplying the electric drive motor at nominal voltage of 230 volts. The advantage of doing this is to ensure a correct start, which could be, if carried out at reduced speed, hindered for example by a dusting of bearings.

After 5 seconds, the turbines are switched automatically on a speed v2 corresponding to an operation silent, the supply voltage to the turbine engines being 170 volts.

This speed regime is maintained for example for 5 minutes (t ₁ ) and during this time, the ambient temperature, illustrated by the segment S1 in FIG. 2, increases and goes from level a to level b.

If during the period t ₁ , the ambient temperature has risen by a level below a predetermined threshold, fixed in the illustrated case at 0.15 ° C., the turbines are switched to a higher speed v3 corresponding at a supply voltage of 190 volts and maintained at this speed during the time period t ₂ , also fixed at 5 minutes.

The ambient temperature S2 changes from level b to level c. At this time, the temperature rise is measured from the level a and if this rise, reduced to the sum t ₁ and t ₂ , is less than the above threshold, that is to say if the temperature rise is lower than 0.3 ° C reduced to 10 minutes, the turbines are switched to speed v4, intermediate between v1 and v3 and corresponding to a supply voltage of 210 volts and, for a period of time t ₃ of 5 minutes.

During this time t ₃ , the ambient temperature S3 goes from level c to level d.

If the level b is such that the temperature rise brought back to time t ₁ is greater than said threshold (0.15 ° C / 5 min), the speed phase v3 is not engaged, but the speed phase v2 is continued during a new period t ₁ . At the end of this second period t ₁ , it is again determined whether the cumulative temperature rise over these two periods t ₁ and reduced to 10 minutes is less than or greater than said threshold. If it is lower, then we go to the speed regime v3. If it is higher, the same speed regime v2 is continued a third and last time, for another same period t ₁ . At the end of the third period t ₁ , we automatically go to the speed phase v3.

The same process possibly takes place at level c at the end of period t ₂ , which can be repeated twice, under the same conditions as explained above with regard to period t ₁ .

If the temperature level d at the end of t ₃ is that of the set temperature Tc, the operation of the turbines is not continued.

On the other hand, if the level d is less than Tc, the period t ₃ will be extended once or even twice, under the same conditions as for t ₁ and t ₂ , until the ambient temperature has reached Tc.

The installation of course will be designed and adjusted so that normally the period t ₃ does not have to be renewed, except in exceptional circumstances such as for example the prolonged opening of a window of the room.

Of course, at any time within the period t, whether the partial periods t ₁ , t ₂ , t ₃ are unique or repeated, if the ambient temperature reaches Tc, the turbines are immediately stopped.

Increasing the supply voltages of the turbine engines is a simple way to regulate their speeds.

Several known techniques can be used to do this, such as falling resistances, or the forecast of several windings on the motors, or sending bursts of supply waves with sufficiently short periods to avoid jolts.

All turbines or just a part of them can be put into operation during period t. We can also not put in service only part of the turbines with a rotation to better distribute in the nucleus the removal of calories.

The values given above at temperatures Tc, T _{1 as} well as the temperature gradient over time (0.15 ° C / 5 min) can of course vary.

Returning to FIG. 1, it will be observed that after point B, if the ambient temperature Ta ₂ falls again to the threshold T ₁ (point C), we will start a new period t ′ during which piloting will take place. turbines identical to that produced during period t until the ambient temperature Ta ₃ rises to Tc (point D).

At all times, other periods (t ") of dynamic restitution can be established, as long as we are still in the so-called period full hours.

If, during this period, the ambient temperature Ta4 comes, for one reason or another and despite the start of the dynamic restitution regime in accordance with the invention, to drop to a threshold T ₂ predetermined with respect to at the set temperature Tc and below both the latter and the threshold T ₁ , the core will be restarted. This threshold T ₂ is for example fixed at 2 ° C below Tc.

When the ambient temperature Ta ₄ reaches this threshold T ₂ (point E), the revival of the core will be carried out according to the pricing, that is to say one third or two thirds of the power at full pricing and at full power with reduced pricing.

This will jointly enable the start-up of the turbines in accordance with the invention, the rise in ambient temperature Tas up to the setpoint Tc.

In FIG. 1, a third temperature threshold T ₃ has also been shown, determined with respect to the setpoint Tc and below both the latter and the temperature (T ₂ ) for reviving the core.

This threshold T ₃ , called the night setpoint, is for example fixed at 3 ° C below Tc. It is only used during a reduced pricing period, to commission the restitution turbines if the ambient temperature drops to the threshold T ₃ .

More precisely, this amounts to lowering the thresholds Tc, T ₁ by 3 ° so that if the ambient temperature drops by more than 0.5 ° C compared to the new threshold (17 ° C), we will trigger the process of restitution according to the methods explained above, that is to say the control of the speeds of the turbines so as to maintain said temperature in the range 16 ° 5C-17 ° C.

We will now explain the charge mode of the kernel in accordance with the invention with reference to Figure 3.

This figure shows the rate diagram (in percentage of nominal load) core load as a function of time accumulated over 24 hours of turbine operation outside of reduced pricing periods.

In accordance with the invention, the operating time is weighted turbines according to their rotation speed by assigning a coefficient at each speed (or motor supply voltage).

During the full pricing period, the partial durations, thus weighted (td, t ₁ , t ₂ , t ₃ ) of all the periods (t, t ', t "), of the turbines operating are totaled and we determine an abacus (figure 3) corresponding to a given number of hours of operation of the turbines a rate of charge of the core. The rate is maximum, for example 100%, for a maximum cumulative duration of operation of the turbines (for example 11 hours ).

So if the turbines on a given day did not work very well, which means that the heat demand has been reduced, for example because the the outside temperature was mild, so the load overnight this day need not be important. Its rate will then be adapted to presumed needs, based on those actually observed the day before, from the abacus of figure 3.

It should be noted that the values indicated on this chart can be of course modified according to the power of the device (s) control and depending on the power required to heat the room (installed power in relation to losses).

Furthermore, it should also be noted that advantageously and in order to obtain optimum accuracy of the charge level of the accumulator core, the temperature of this nucleus will be measured using a thermocouple at contact of the accumulator core and not as it is done usually in existing devices, using a measuring device placed against or in the thermal insulation which surrounds the core and which does not controls only an approximate "image" temperature.

Figure 4 is a diagram of an electric heating installation comprising an accumulator 10, a radiant panel 11, a convector 12, all connected by a single pilot wire 13 to a multi-position switch 14, for example of the type known commercially as "SESAME doorman".

The control button 15 of the switch allows a positioning in four positions, namely C (Comfort); R (Reduced); H-G (Frost protection) and A (Stop). Control signals conveyed by the driver single 13 and addressed to the command microcontrollers integrated in the various devices 10, 11 and 12 are constituted, in the known manner, by: no signal (position C); alternating full alternating signal (position R) ; lower half-wave signal (position H-G) and half-wave signal upper (position A).

This device allows the user in particular to activate the night setpoint (threshold T ₃ , Figure 1) by placing the button 15 in position R, which lowers the setpoint values of the accumulator 10, its operation remaining, as explained above, the same.

According to a variant, the switch 14 can be replaced by a programmer generator of orders conveyed by the pilot wire 13, so that, in particular the night setpoint is automatically put into service depending on the program displayed.

It should be noted that the pilot wire 13 could be eliminated by using the supply wires of the turbine engines of the accumulator 10 according to the carrier current system, to convey the signals corresponding to positions C, R, H-G, A, by appropriately formatted messages.

Claims (3)

1. Method of regulating the charging and discharging of electric storage heating appliances or the like and notably of the type comprising a core formed from refractory bricks, electric elements for heating the core, and a plurality of fans for the forced circulation of air to be heated in channels in the core, the method comprising:

   A/ with regard to the discharge or restoration:

   triggering the switching on of at least one fan when the temperature measured in the room where the appliance is situated falls below a first threshold (T₁) predetermined with respect to the set temperature (Tc) displayed and below it,

   modulating, each time the fan or fans are switched on, their speed of rotation in accordance with the following successive phases:

   v1: nominal speed, for a predetermined period;

   v2: speed reduced to a first level for a predetermined period,

   v3: speed brought to a second level higher than the first, for a predetermined period,

   v4: speed brought to a third level intermediate the nominal speed and the second level, for a predetermined period;

   - the passage from one of the modes v2 and v3 to the following mode being made only if the following two conditions are fulfilled:

   1) the temperature of the room is less than the set temperature (Tc);

   2) the rise in temperature in the room throughout the phase which has just ended is below a predetermined threshold;

   - each phase v2, v3, v4 being, if said temperature rise, at the end of the phase in question, is greater than said threshold, recommenced under the same conditions, a given number of times;

   - and the stoppage of the fans being demanded at any time as soon as the temperature of the room reaches said displayed set value (Tc);

   B/ with regard to the charging of the core:

   1) during the reduced-tariff hours:

   a) cumulating, over 24 hours and outside said reduced-tariff hours, the operating times of the fans by weighting these times according to the speed of the fans in each operating period;

   b) and, according to a nomogram for the percentage charging as a function of the total thus accumulated of the fan operating times, determining a percentage charging of the core and limiting the charging of the core the next day to this percentage;

   2) during the restoration hours:

   a) restarting:

   if, at the end of the succession of said phases v1 to v4, the rise in temperature in the room during the total operating time of the fans is less than a predetermined threshold,

   or if the temperature of said room reaches, whilst falling, a second threshold (T₂) predetermined with respect to the set temperature (Tc), on this side of said first threshold (T₁),

   b) and stopping the restarting as soon as the temperature of the room reaches said set value (Tc).
2. A method according to claim 1, characterised in that, for a functioning in reduced mode, a signal (R) is sent to a microcontroller of the appliance (10) preventing the starting of the restoration fans, unless the temperature of the room falls below a third threshold (T₃) with respect to the set temperature (Tc), less than the second threshold (T₂), the charging circumstances of the core remaining unchanged.
3. A method according to claim 1, characterised in that the end of the charging of the core is controlled from the measurement of the temperature of the core by means of a thermocouple in contact with said core.

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