GB2410790A - Micro combined heat and power engine with thermal storage apparatus - Google Patents

Abstract

The invention relates to the combination of micro combined heat and power engine in operation with thermal storage apparatus whereby the operation of the mCHP can be selective, depending on the condition of a body of water within the thermal storage apparatus and, furthermore, the particular mode of operation can be selected with reference to the condition of the body of water. If required, an auxiliary heater can be provided in the thermal storage apparatus which can be selectively operated if the demand for heated water is not being met by operation of the mCHP. Furthermore, other operating parameters can be referred to such as, for example, the particular time of operation of the mCHP with respect to electricity demand and the possibility of obtaining revenue from electricity generated by use of mCHP at particular times.

Description

24 1 0790 Thermal Storage and mCHP Apparatus The invention to which this

application relates is the provision of a thermal storage apparatus <>f a type used to provide water and/<>r heated water for central heating purposes and particularly, but not necessarily exclusively, the provision of a thermal store in a domestic premises.

Furthermore, the invention provides the ability to combine use of the thermal store with a micro combined heat and power engine (hereinafter referred to as "mCHP") and to use the thermal stc>re apparatus in an advantageous manner with the said m( HP.

lithe provision <>f thermal store apparatus to provide heated water for central heating purposes or to supply taps is well known and the applicant, and others, have many granted patents and patent applications relating to the same. Normally, the term thermal store apparatus is used to distinguish this apparatus from a hot water cylinder system but it can more accurately be referred to as a store of "primary" water, i.e. water which passes through the radiatc>rs and boiler connected to the thermal store rather than "secondary" water which is stored in a cylinder in most domestic installations. Thus the thermal store allows the supply of hot water, in combination with a body calf water held in a tank with the water being drawn off the tank t<> be heated and therefore acting as a thermal store through which further water can pass and, as it passes through, the same is heated.

l he use of a m(,T IP is also known, with the same treated as a heat source and used to replace a boiler. H<>wever, it is found that in practice, the M(-HP, in operation, cycles too frequently inasmuch that the same switches on and off a number of times over a relatively short period of time. As m( HP's, such as that

.e e e.e e e e- . e : . ..e:. . . t..DTD: offered by WhisperGen_, require a relatively long running time (8-15 minutes) to reach operating conditions because of time required to establish temperature difference between hot and cold sinks of the engine and to allow the same to be synchr<'nsed with a mains power supply and the like, therefore there is a significant period of time before the mCI 11' reaches the required speed and operating conditions to provide a required heating effect. 'the same is true when the engine is switched off i.e it could take 5-10 minutes for the engine to power down because the residual heat from the engine must be removed to prevent damage. Further, the unit does not modulate to match the load. All these could result in excessive cycling and temperature swings. In addition to this being disadvantageous to the user, it is found that the frequent cycling can also adversely affect the life of the m(,HP.

One market for the m(HP appliance is the existing housing stock where the boiler and/or heating system is being upgraded.

l'he vast majority of heating systems in these dwellings will be one of the following two types: (a) lumped heating and hot water based on 'Y' or 'S' plan control system with motorised valves and pump in the hot water cylinder cupboard. 'lherefore in the cylinder cupboard there will be boiler flow, boiler return and heating flow pipe connection will be available.

(b) (gravity circulation to the hot water cylinder and pumped heating. In this type of system the pump will be adjacent to the boiler and only boiler flow and boiler return pipe connections will be available in the cylinder cupboard.

. ... ... . .. - . . . . . . . . . . . . . . . .. . . . t Therefore the mCHP is preferred to be suitable for this retrofit market with minimum changes to the existing inaccessible pipeworl.

I f the existing hot water cylinder is tatted with an immersion heater, then a 1 6A electricity supply will be available in the cylinder cupboard and the cable for this supply may be suitable for up to 20A which limits the auxiliary electric heater power rating to 4.5kW.

The aim calf the present invention is to> provide an improvement to the operation to the mCHI' apparatus such that firstly, it improves the life of the same and, secondly, allows the same to be used in a commercially viable manner.

In accordance with a first aspect of the invention, there is provided apparatus f->r the generation of heat and/or electricity, said heating apparatus including; a micro combined heat and power engine (mCHP) in connectic>n with a thermal store apparatus, the thermal store apparatus includes a body of water and at least one sensor provided in the thermal store apparatus to monitor a condition ' f said body c>f water, characterised in that the mCHP is selectively operable in at least two Operating conditions and the selection to change Operating condition of the m(,T 11' is made in response to a detection by the sensor of a predetermined condition.

In one embodiment the said water is maintained within a substantially clc> sel system. In one embodiment, the thermal store apparatus includes a body of water and at least one, sensor provided In the thermal store apparatus to monitor the e.e *. ..

. . . . . . . . . . condition of the said body of water and, in response to predetermined sensor data the m(HP can be moved to an -'peratng condition.

In one embodiment the sensor detects the temperature of the water. 'l'ypically two or more sensors are provided.

lypically, the mCHP can be moved from the off operating c-'nditon to one of at least two other -'perating conditions, one contlition being a normal mode of operation and a second condition being a boost mode of operation, with a mode of operation selected dependent on the data received from the said sensors.

l'ypically the sensors are provided at spaced locations in the body of water of the thermal storage apparatus.

In a preferred embodiment, the body of water is provided in connection with a first circuit for the provision of heated water for central heating purposes.

l'ypically, In cooperation, when the sensors in the body of water are referred to and it is found that the temperature of the body of water, in both sensors, has dropped below a certain level, then this indicates that a demand for heating is present and, when rc-4urecl, the m( l-1P is started to operate in a normal mode to provide the heat source for the body of water to which the same is connected. ltypically, at a predesignated time interval thereafter, such as, for example, every second, or for certain sensors many times a second, the sensors condition is again referred to. If it is found that the demand is being met, in that the temperature of the water has not continued to fall, then the m(2HP continues to Operate. I-Iowever, if it is found that the temperature is still falling and hence demand is still not being met by operation of e bee eee eve e e e e e ëe e e e e e e e e e e e e ee e e e e e e e the mCHP in a normal mode, then the operation of the mCIIP can be moved to a boost mode in which greater heat is provided.

Thereafter, if upon a further referral, it is found that the demand Is still not being met, then an auxiliary heating device can be provided in the thermal store apparatus which can be activated to provide a further increase in the heating effect on the body of water.

Thus, one of the advantages of using a thermal store with an m( Hi' engine is that although the engine takes a relatively long time to' build up to maximum output, say for example, a time period of 15 minutes, and which conventionally would be too Icing a period after a request for heat is made for practical use in heating systems, because the thermal store is provided, the radiators in a property will be giving out their full heat in approximately 2 minutes after the request for heat is made, such as by the householder activating the room thermostat when the thermal storage device is in operation. Similarly the requirement for domestic hot water can be met from the primary store at any time. al bus thermal store acts as a buffer to allow the m(_l IP engine to get up to speed to meet the long term heating requirements while the short term requirements of the user for heating to be provide d soon after a request has been made, is met by the provision of the thermal store operating in conjunction with the m( HP.

Further advantages of using a mCHP device with thermal store are: a) when the demand for space heating stops i.e. room thermostat is satisfied, the engine can safely power down and dump its residual heat into the thermal store without overheating the dwelling and hence avoid wasting the energy.

the stored energy can then be used during the next heat demand cycle.

ee. *.e ee.

e e e e e e e e e - . e e e e e - b) that even if the power supply to the premises in which the apparatus is provided fails, the mCHP, due to its nature, will carry on running for a period of time and will produce power ancl, in this case, the control of the pumps of the apparatus is passed to the mCI-ll' to allow heat to be passed from the mCHP to the thermal store in a controlled manner for use when power is restored.

In a prcfcrrcd embodiment, and to reduce the cycling of the m( HP, at least twit sensors are provided at spaced locations in the body of water of the thermal store and the m(,HP will not be caused to start operation until a demand is sensed from both of the sensors. '{he demand is indicated by the temperature sensed by both sensors falling below a predetermined level.

Typically, the hot water which is provided from the mC:HP to the body of water, is introduced at the top of the body of water in the thermal store and the mCHP will not switch off until the lower scusor is satisfied by the body of water at that location reaching a suitable tcmperaturc.

In a further embodiment of the invention, there is provided control means to determine the optimum times at which the m( Pll' can be switched on. For example, as the m(,HP can also provide electricity energy, in addition to the heating of the water, the m( IIP can be used as an electricity source. As such, the clectrcity which is generated from the m( HP can either be used for other purposes within the premises in which the same Is installed or, in addition or alternatively, can be passed on to the National Grid or electricity provider organisation who make a payment for the received energy. In order to monitor this aspect of the invention, a 2-way meter can be installed at the premises, a first part of the meter measuring consumption of eaee e.- e eee ë ee ee. ë * e e e * e e e e e e electricity entering the premises in a conventional way and the second part:' f the meter monitoring electricity which is provided from the premises via the m(:HP and which leaves the premises.

In order to achieve the optimum gain from the provision of electricity from the m(,HP, the control means monitors when a demand for operation c' f the m(,HP occurs and also monitors the level calf demand in whether there has been a relatively small decrease in temperature or a significant decrease in temperature.

In one embodiment, the control means then compares the time of the request for demand with the pre-programmed times at which electricity is at the peak price. If the times match, then the m( HP will be turned on immediately, regardless of whether the demand is significant or normal. If the times don't match but there is only a short period of time until the peak electricity price time periods occur, then if the demand is only a normal demand, the control means may select to act to delay the operation of the mCHP until the peak electricity time period arrives. If the demand is significant however, then the control means may deem it necessary to switch on the m(,lIl' but only in a normal mode and move the mCHP to a boost mode, if the demand Is maintained once the time period of the higher electricity price requirements arrives. In this way, firstly, any electricity which is generated can be used within the premises to meet the demand for electricity in the premises at that time and thereby prevent the owner of the premises using electricity from the external electricity provider and, if there is still excess electricity, that electricity which is go nerated from the m(,HP can be passed onto the external electricity grid for which the owner of the premises will receive a payment and, especially if the mCHP is controlled to operate at peak electricity price time periods the benefit to the owner is optimised. .

en. . *e.

Thus, In accordance with the invention, there is provided the combination of use of a thermal store with the mCl11' which in itself is a novel and inventive step. lis a result of this combination, significant advantages can be obtained in terms of the efficient control and operation of the mCIIP, the ability to use the m(,HP ancl thermal store apparatus in domestic premises and, yet further, the ability to control and utilise the electricity which is generated from the m(:,HP to economic benefit to the owner of the premises in which the same is installed.

In one embodiment of operation the thermal store has overall control calf the system with three pumps provided which are; (a) 'l'he engine pump which is under control of the mCHP.

The engine gets its run signal in the thermal store and the engine run signal is not necessarily time- controlled.

(b) 'l'he second pump is the central heating pump which operates on a time clock, with room thermostat override.

(c) 'lthe third pump is the Domestic Hot Water (DHW) pump which pumps water from the thermal store through a plate heat exchanger which acts to heat incoming mains pressure cold water, and deliver mains pressure hot water to the tap s.

It should be appreciated that different variants of thermal store can be incorporated in this invention. For example a thermal store with diverter valve and single primary system pump, which Is primarily for use in retrofitting to existing systems is covered within the scope of this invention as is the thermal store which has twc' primary pumps, one for space heating and one for the m( Hl', which is primarily for installation in newly built premises.

* doe ate e eve e e e ea. . e a a a a.

a e e as a e . e In a further aspect of the invention there is provided a method of controlling the operation of apparatus for generating heat and/or electricity, said apparatus including a micro combined heat and power engine (m(,HP) in connection with a thermal store apparatus, said method comprising the steps of including in the thermal store apparatus at least one sensor for detecting the temperature in the body of water of the thermal store apparatus, setting the sensor to generate a signal when a predetermined temperature is detected, characterised in that the m(,l IF is selectively operable at least between on and off conditions and the selection of the operating condition is changed In response to the detected signal received from the sensor in the thermal store apparatus.

In one embodiment following the change of operation condition, a further change in operating condition can be made following a further temperature detection from a sensor.

In one embodiment the change to a particular operating conclit1cn lasts for a predesignated period of time. AIternatively the change to a particular operating condition lasts until a predetermined temperature is detected.

Specific embodimcuts of the invention will now be described whcreln: Figure 1 illustrates a schematic diagram of one embodiment of the invention; leisure 2 illustrates in more detail the temperature sensors used in the thermal store in accordance with the invention and a key to the variables and constants used in the algorithms and programme for control of the same; e car s a ae Figures 3 and 4 illustrate flow diagrams of the logic used in the control system; and Figures 5-lO illustrate graphically performance of one specific example of the invention.

lieferrng firstly to L'igure 1, this illustrates a typical arrangement between a thermal store and an m(,T IP in accordance with the invention. The m(,HP 2, is connected to the thermal store via an m( HP pump 4 and two electric heaters 6. 'lithe thermal store itself is provided with a tank with temperature sensors Sl and S2 spaced apart within the body of the tank, as shown. The thermal store, in turn, is connected to a plate heat exchanger 12 which allows the supply of hot water 14 upon receiving cold water therein, 16. 'I'he water from the tank to the plate heat exchanger is provided via the pump 10.

lthe thermal s tore is also connected, in this embodiment, to a space heating system within the premises 22 via circuit 24 which inclucles a heating pump 26.

In this embodiment, the circuit for the control of the arrangement as shown in figure 1 is set such that if the temperature sensor S1 has a temperature of less than 50"C and S2 sensor has a temperature calf less than 65"C then the mCHP is switched on to provide the required energy to heat the water above those temperatures. If the temperature of S1 is greater than 70"( and S2 is greater than 75"C then the mCHP is off and if S1 is greater than 85"C and S2 is also greater than 85t'C then the m( HP is off.

In atlditic>n to the cooperation of the m( HP in the normal mode, if the temperatures of S1 and S2 drop quickly to a relatively low temperature, say for example if S1 is less than 40"(2 and S2 is : ... e: :. . . . . : . . . : : : . less than 50"C, then the mCHP can be switched on and also moved to a boost mode In which increased heating capacity is provided so as to heat the water more quickly as the significant drop in temperature indicates that there is a particular demand on the requirement for hot water at that time.

Furthermore, if the temperature of S2 is detected as being less than 50"(, and the rate of S2 temperature rise is less than 4"C with the m( HP on, then the system senses that there is insufficient heating occurring to meet the demand and hence both of the auxiliary heaters are switched on, these typically each being 4.5kw heaters. If the temperature of S2 is less than 55"( and the rate of S2 temperature rise is less than 4"C then one of the auxiliary heaters can be switched on.

If, or when, the temperature of S2 is greater than 52"(, and the rate of S2 temperature rise is greater than TIC, then no auxiliary heaters will be switched on or the auxiliary heaters will be switched o ff if they have been on. Similarly, if S2 is greater than 57"( and the rate of S2 temperature rises more than 4'C then no auxiliary heaters are on, or if they have Leon on they will then be switched off.

It will therefore be appreciated that the temperature sensors take the temperature of the water in the tank at regular intervals, thereby allowing the monitoring of the water to occur at regular intervals and the m(,l IP to be switched off, on or moved to a boost mode, can be constantly selected as can the need for switching- the auxiliary heaters on or off.

Iigure 2 illustrates in more detail, the control systems and configurations for the mCHP and thermal store arrangement.

e ee eee e eve e e e e e e e e e Figures 3 and 4 illustrate, respectively, flow diagrams for the control of the mCHP on/off with the numerals 1'1 and T2 inclcating the temperatures from the sensors S1 and S2 respectively. I'igure 4 illustrates the mCHP switch control logic in detail.

specific example of the variation is now described. In this example the thermal store operates with reference to two temperatures, one taken by sensor (S1) close to the bottom of the store (bottom temperature), and the other taken by sensor (S2) located approximately a third of the way from the top of the thermal store (top temperature).

the control logic for operation of the engine is as follows: liemperature (S2): on 65"C off > 75"(_ l'emperature (S1): on < 500(, c>ff > 70"(, l'he m( FlP is called for when both top and bottom temperatures are "on"; and Lyle m(,HP is given the off signal when both top and bottom temperatures are "off".

If there is no, or little, stratification within the thermal store, the thermal store operates between approximately 50 and 75"( (Stratification widens the band of operation). In this example, the storage volume is approximately 188 litres, which equates to approximately 19,425 kj (5.4kWh) of thermal storage. Hence, with no external (central heating or DT TW) heat demand, the ACT ll' would reheat the tank in under 1 hour at the 6kW nominal output.

In addition to the heat provided by the mCHP an electric flow boiler is provided which can provide heat if the thermal store is not being reheated fast enough and/or can act as a backup if the mCIlP fails. In this example the flow boiler has a 9kW output

.. e....DTD: : :e . :: arranged in 2 banks of 4.5kW, but in this example the flow boiler was not required.

The m( 1TP also includes a thermal management routine with a setback condition (power level 1) set close to the normal output of the engine (power level 2) and so allowing the mCHP to generate at high efficiency at all times.

In order to monitor the performance in the example a demand for central heating and no demand for central heating was simulated. l;igure 5 shows data for a full day (plus 2 hours either side to show trends more clearly) where there was a demand for central heating. A schedule of automatic DHW draw-offs is also implemented (12 draw-offs with a total of 155 litres/day). Lyle graphs show water temperatures for tS1 (bottom) and S2 (top) of the tank, and the mCHP flow and return. 1 t also shows mCHP heat output (calculated from the measured flow and return temperatures and the water flow rate) and the m( l lP electrical power output (shown on the same scale as the heat output, with values multiplied by 10). Any spikes in the calculated heat output are due to transients in the flow and return temperatures at start up and there may also be electrical power transients at the time of start up.

Lyle m(111' switches off late at the end of the previous day with the thermal store fully charged and thereafter the temperatures Sl and S2 show signs of stratification over night, with the bottom temperature cooling faster than the top temperature.

The central heating is called for at 7am and there is a significant fall in tank temperature as the cold water in the radiators is displace] by the incoming hot water and makes its way into the store. lis a result the mCHP is switched on.

e ee ece e ace e e e e e e In the example the mCHP runs for four periods of the day - the shortest period being for just over 1 hour. This compares fav-'urably with mCHP bchaviour which has been observed where no thermal store is used and, when at times the m(',HP would cycle continuously every 15 to 30 minutes.

lithe call for the m(,HP is removed when the store temperature S2 exceeds 75"C. However, the control system keeps the m(,HP running at reduced output until the flow temperature reaches the maximum of 83"C (8"(, above the setpoint of 75"(,) so that the pump continues to run for another 30 minutes.

1-the initial rapid cooling of the thermal store is illustrated in ligure 6. In the example central heating is called for at 7:00 (30 mins on the x-axis). After the initial fall in temperature, the top and bottom tank temperatures quickly converge and all tank stratification disappears. '{he mCHP engine comes on some 20 minutes after the central heating and takes 15 to 20 minutes to establish its full output of heat and electricity.

Figure 8 shows room and central heating water temperature for the corresponding day and shows the widely varying central heating water temperatures (following closely the tank tcm}craturcs shown in I igure 6). However thctc is little or no effect on rc>->m temperatures, since the thermostatic radiator valves adjust the flow rate to compensate.

lihc example illustrated in I-igurcs 5 to 8 shows an early morning start after the thermal store had been heated to its full capacity at the end of the previous evening. If the m(,lIP is not running when the central heating is switched off and the store will be at a lower temperature at the start of the next central heating pcricd as shown in Figure 9. Here the store is at some 65"(, when the central heating goes off (21:00 day 1) . When the ha. ': :. ' : e:: . : . : ,. .... ::: . central heating comes back on (7:00 day 2) the store temperature quickly falls below the m(,l IP run threshold and the mCHP comes on almost immediately.

l'hc Initial start period is shown in more detail in Figure 10.

lithe lowest mixed temperature (when the top and bottom temperatures converge) is 45"(, compared to the 55"C in Figure 7 and so does not differ greatly from the lowest mixed temperature in Figure 7 (just after the mCHP is called for) of 47"( and therefore even with a low starting store temperature the m( HP behaviour is not significantly different from that with a fully charged store initially.

In a start up with the store depleted so that it is unable to provide adequate Dl IW when required (both in quantity and temperature), the test was conducted where, after the m(LlP has cycled off, the central heating is left running until the store temperatures are reading 55''C. The central heating is then switched off and the house allowed to cool so that the central heating is switched back on after the radiators have cooled to room temperature and water is drawn from the taps.

the lowest mixed tank temperature which occurs after the central heating is switched back on is 42"(. Despite this, there is plenty of hot water with 70 litres were drawn off before the water begins to feel too cold to wash in. l'he thermal store therefore generally has sufficient capacity to provide adequate 1)WEI even if the store is depleted prior to the start of central heating In a full day's operation, with no demand for central heating, the same pattern of hot water draw offs is adopted as for the previous tests. (155 litres in 24 hours; amounts varying : ." A: :. ' ::: . .: . : .. ,. -. ; : ; . r throughout the day; no draw offs between 10:00 and 17:00; largest draw <->ff 40 litres at 17:00).

The stratification of temperature within the tank is much more pronounced when there is no demand for central heating. In tints situation the store is able to operate over a wider temperature range - the bottom temperature falling to 32t'(, before the top temperature falls to 65"(, and calls for the m(,HP.

-typically there is one m(,HP run per day of just over 1 hour duration - a reasonable period of full engine output. The time when this occurs is not controlled in any way. ':Lhe thermal store overcomes the problems associated with rapid cycling and short run times when the heat demand is low. Positioning calf the control temperature and tank return pipes is such that there Is always a good supply of hot water for DHW production, even just after switching on the central heating when there is a rapid Influx of cold water from the radiators.

l'he biggest demand for heat is normally at the start of the central heating period and it is prudent to have the mC,HP running at this point. This can be achieved by giving the m(, I Tl' a run signal when there is a rapid change in the store temperature as well as when the actual temperatures signify a demand. 'lihus, in a situation similar to that shown in Figure 6, the m(:l IP will start almost immediately after the central heating.

further improvement is to integrate the timer into the control logic' such that the m(,l-lP can be activated ahead of a known significant demand for heat.

It is also possible to leave the store partially depleted (by a controlled amount) so that the m(,l IP has a small demand to meet during its start up phase, and the store can then be fully e e as.;. ese . A. a e e < e; r chargecl, with the mCHP running at full output, by the time the central heating demand actually occurs. An alternative is to analyse taking theelectrical consumption pattern and optimise the m(,HP run times to coincide with maximum electricity demand, and allow the store to partially cleplete at other times.

Variations in flow temperature can lie reduced by incorporating a thermostatically controlled mixing valve between the thermal store and the central heating system - with radiators designed and a mixing valve set for a temperature of, say 50"(,. 'this recluces the danger of very hot temperatures, especially in a non thermostatically controlled radiator. It may also reduce the initial fall in temperature of the store when the central heating is htst switched on (as some of the cold radiator water would be recycled, and not fed into the store).

l'rovision can also be made for inclusion of a simple time clock which can be used to control periods of operation at undesirable times, e.g. overnight, when there is little electrical demand and occupants arc sensitive to noise intrusion. Use of the time as part of the control logic can be used to prioritise engine operation for set times of the day (e.g 6 to 8 pm) with lower priority times set to always ensure that an adequate supply o f DOW can be achieved.

I'ypically the m(,Hl' has several power output levels: Tower I,evels Electrical output Thertnal output 1'1 Setback See above P2 Nominal ().85 kW 13.3 I30:>st 1.4 kW 8.2 kW 1'4 Boost plus ntcrnal heater ().4 kW).2 kW 13<>ost plus external heater 1.4 kW X.2 + external e e-e see e see e e e e e e see e e e e a e e e e e e e e e e e e e ee e e e e e e e e e The mCI-IP management routine moves through the power output levels according to both the rate of temperature rise of the coolant and the actual temperature of the coolant relative to the engine set-point. During the tests described the mCHP would Only have called for power levels 1, 2 and 3.

l'roviding the temperatures are within the upper and lower bands (i.e in this case 50 to 75"C) and the mCH1' is operating then the temperature of the store can be allowed to increase (eventually filling the store and switching the mCHP off) or can be allowed to stay the same so that the total heat load is well matchecl to the heat input from the m(,l-lP or the temperature can be allowed to decrease so long as the store will not be completely depleted before the end of the current heating period. thus, the current heating period can be satisfied and the store will be replenished when there is no heat demand (or lust a demand for DI IW) at the end of the current heating period.

l bus, whilst rate of change of store temperature is one method of ensuring adequate thermal storage, it will not take full advantage of the possibilities of thermal storage, and may mean a call for supplementary electric heat when this could be avoided. IIowever if the rate of change of temperature criteria is used, the rate should be set at a much smaller level with a thermal store than with no store, because of the volume of water that is being handled and because of the assumption that provided the temperature is within its control band it can meet the heat output requirements.

l he current invention which combines the mCHP with the thermal store provides a solution to the problems of rapid m( lip cooperation cycling which occurs conventionally. The number of starts of the m( Hi' are significantly reduced and run e e : : times increased, giving improved output and increased efficiency.

eee e-. a e e e e bee e e e > e e e e e be e e

Claims (1)

1. Claims 1. Apparatus for the generation of heat ancl/or electricity, said

   heating apparatus including; a micro combined heat and power engine (m( HP) in connection with a thermal store apparatus, the thermal store apparatus includes a body of water and at least one sensor provided in the thermal store apparatus to monitor a condition of said body of water, characterized in that the mCHP is selectively operable in at least two operating conditions and the selection to change cooperating condition of the m(,Hl' is made in response to a detection by the sensor of a predetermined condition.

   2 Apparatus according to claim I wherein the said water is maintained within a substantially closed system.

   3 Apparatus according to claim 1 wherein the operating conditions are an cuff condition, a normal operating condition and/or a boost operating condition.

   4 Apparatus according to claim 1 wherein the operating condition of the mCI IF is selected in response to a predetermined condition of said body of water.

   Apparatus according to claim 1 wherein the sensor detects the temperature of the water.

   (I Apparatus according to claim 1 wherein at least two sensors are provided at spaced locations in the body of water in the thermal storage apparatus.

   * e e e e e ate e e e e e e e. e e 1 1 7 Apparatus according to claim 1 wherein the body of water is provided in connection with a first circuit for the provision of heated water for central heating purposes.

   8 Apparatus according to claim 1 wherein if it is found that the temperature of the body of water has dropped below a certain level, a demand for heating is determined and the m( l IF is started to operate in a normal mode.

   9 Apparatus according to claim 8 wherein after a predctctmincd period of time of operation, the sensor condition is again referred to.

   Apparatus according to claim 9 wherein after further refcrcncc to the condition of the sensor, if the temperature of the water is equal to or less than the previous sensed temperature the mCI It' is moved to a h'ost mode of operation.

   11 Apparatus according to claim 10 wherein further reference is made to the sensor upon operation in a boost mode and, if the temperature of the water is equal to or less than the previous sensed temperature an auxiliary heating device is 'pcrated in the thermal storage apparatus.

   12 Apparatus according to claim 1 wherein the mCHP can be moved to an cooperating condition with regard to the condition of at least two sensors provided at spaced locations in the body of water in the thermal store.

   13;\pparatus according to claim 12 wherein the mCHP is not moved to an operating condition until data from both sensors meet predetermined criteria.

   e e e e e e e ee ee e e e e e e e 14 Apparatus according to claim 13 wherein the condition of the sensors which activates the operation calf the m(,HP is that the temperature sensed by both sensors falls below a predetermined level.

   Apparatus according to claim 1 wherein the hot water which is provided from the mCHP to the body of water is introduced at or adjacent to the top of the body of water in the thermal store.

   l Apparatus according to any of the preceding claims wherein control means are provided to determine the optimum times in any given time period at which the m( HP is preferred to be operated in a selected operating condition.

   17 Apparatus according to any of the preceding claims wherein when the mCHP is operating electricity generated by the same can be selectively supplied to the electricity grid to which the Mchp is connected.

   18 A method of controlling the operation of apparatus for generating heat and/or electricity, said apparatus including a micro combined heat and power engine (mCHP) in connection with a thermal store apparatus, said method including the step of including in the thermal store apparatus at least one sensor for detecting the temperature in the body of water of the thermal store apparatus, setting the sensor to generate a signal when a predetermined temperature is detected, characterized in that the m( HP is selectively operable at least between on and off conditions and the selection of the operating condition is changed in bee see .e e . - e . e e . . ( I r response to the detected signal received from the sensor in the thermal store apparatus.

   19 A method according to claim 18 wherein following the change of operation condition, a further change In operating condition can be made following a further temperature detection from a sensor.

   A method according to claim 18 wherein the change to a particular operating condition lasts for a predesignated period of time.

   21 A method according to claim 18 wherein the change to a particular operating condition lasts until a predetermined temperature is detected.

   22 Apparatus as hereinbefore describel with reference to the accompanying drawings.

   23.1\ method as hereinbefore described with reference to the accompanying drawings.

   e eee bee eee e e e e e e as- e e e e e e e e e e e e e e ee e a e e e e e e