GB1561020A - Apparatus for determining the efficiency of a heating appliance - Google Patents

Apparatus for determining the efficiency of a heating appliance Download PDF

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Publication number
GB1561020A
GB1561020A GB5054977A GB5054977A GB1561020A GB 1561020 A GB1561020 A GB 1561020A GB 5054977 A GB5054977 A GB 5054977A GB 5054977 A GB5054977 A GB 5054977A GB 1561020 A GB1561020 A GB 1561020A
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United Kingdom
Prior art keywords
efficiency
temperature
dial
flue gases
carbon dioxide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB5054977A
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Nederlandse Gasunie NV
Original Assignee
Nederlandse Gasunie NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nederlandse Gasunie NV filed Critical Nederlandse Gasunie NV
Publication of GB1561020A publication Critical patent/GB1561020A/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D1/00—Measuring arrangements giving results other than momentary value of variable, of general application
    • G01D1/16—Measuring arrangements giving results other than momentary value of variable, of general application giving a value which is a function of two or more values, e.g. product or ratio
    • G—PHYSICS
    • G12—INSTRUMENT DETAILS
    • G12B—CONSTRUCTIONAL DETAILS OF INSTRUMENTS, OR COMPARABLE DETAILS OF OTHER APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G12B11/00—Indicating elements; Illumination thereof
    • G12B11/02—Scales; Dials

Description

(54) APPARATUS FOR DETERMINING THE EFFICIENCY OF A HEATING APPLIANCE (71) We, N.V. NEDERLANDSE GASUNIE, a Netherlands Limited Liability Company of P.O. Box 19, Groningen, the Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to apparatus for determining the efficiency of a heating appliance, which apparatus comprises measuring instruments for generating electrical signals responsive to the temperature, and to the oxygen content or the carbon dioxide content of flue gases leaving the heating appliance.
The efficiency of heating appliances for example central heating installations, geysers and boilers may be measured according to the equation heat supplied-heat of flue gases heat supplied The heat supplied is the amount of calories theoretically produced by complete combustion of the fuel used. The degree of efficiency is affected by the design and operating conditions, particularly in the fuel/air ratio.The percentage of heat loss (heat supplied-heat of flue gases) is approximately represented by Siegert's equation T-t w=f [CO2] in which w=percentage heat loss at complete combustion; f=the so-called Siegert coefficient, which is dependent on the fuel; T=the temperature of the flue gases. "C: t=the temperature of the combustion air supplied, OC; [CO2l=the carbon dioxide content of the flue gases, /, by vol.
Siegert's coefficient, f, is not quite constant for any given fuel, but is to some degree dependent on the carbon dioxide content of the flue gases, [CO2].
If not the carbon dioxide content, but the oxygen content of the exit gases is measured, the percentage loss is approximately represented by a similar equation T-t w=f' [O2latm[O2] in which f'=a coefficient (different from f) dependent on the fuel; [O2]=the oxygen content of the flue gases, /n by vol; [O2]atm=the oxygen content at atmospheric pressure of the combustion air supplied, /n by vol.
In most instances the oxygen content of the combustion air is 21 '.
It is found in practice that the heating appliance is not adjusted for optimum efficiency. One reason is that the separate measuring of the flue gases and the quality of the flue gases, i.e. the carbon dioxide content, or the oxygen content of the flue gases or a function of the combustion air supplied, and the calculation from these measurements of the efficiency by means of Siegert's equation, is too complicated and time-consuming for the average operator.
Thus there is a requirement for apparatus which can indicate simply and rapidly the degree of operating efficiency, and also for indicating the cause of the operating efficiency not being a maximum.
It is the object of the invention to provide apparatus which will fulfil the above requirement.
The invention provides apparatus for indicating the efficiency of a heating appliance, which apparatus comprises two measuring instruments for generating electrical signals in response to the flue temperature, and to the carbon dioxide content of the flue gases or the oxygen content of the flue gases as a function of the oxygen content of the combustion gases supplied, respectively, and the said signals each effect a corresponding swing to a respective indicator arm of a pair of intersection indicator arms, and a dial calibrated into a plurality of areas each corresponding to an indicated degree of efficiency, whereby the point of intersection of the said indicator arms when viewed in conjunction with the said dial provides an indication of the efficiency of the said heating appliance under operating conditions.
If measurements are made of the temperature and the carbon dioxide content of the flue gases, the dial of the apparatus according to the invention is characterized by diagram lines indicating constant efficiency for efficiency values not differing by more than an amount of 2% from 82.5 /n, 780,, and 72 ," as calculated from the equation:
in which lpoperating efficiency at complete combustion; iCO2]=the carbon dioxide content of the flue gases, % by vol; T=the temperature of the flue gases, OC:: t=the temperature of the combustion air supplied, OC; b, c and d=constants whose values depend on the fuel used in the said heating appliance and do not differ by more than 10"" from the following values: b=0.34 c=0.0076 d=90.
If measurements are made of the temperature and the oxygen content of the flue gases, the dial of the apparatus is characterized by diagram lines indicating constant efficiency for efficiency values not differing by an amount of more than 2% from 82.5 ,/" 78 Mn and 72% as calculated from the equation:
in which: ri, T, t, d and c have the same meanings as hereinbefore defined, and [O2]=the oxygen content of the flue gases, by by vol; [O2]atm=the oxygen content of the combustion air supplied, % by vol; a=a constant the value of which depends on the fuel fired in the heating appliance and does not differ by more than 10% from the value a=0.78.
Preferably the said indicator arm which is connected to the measuring means for flue temperature registers with a scale on the said dial calibrated for flue temperature.
Preferably the said indicator arm connected with the measuring means of the carbon dioxide or oxygen content of the flue gases, registers with the pointer giving an electrical indication of the quality of the flue gases, which pointer has a scale division showing the air excess. The term 'air excess' is hereby defined as a quantity n satisfying:
in which: [O2]=the oxygen content of the flue gases, by by vol; [O2]atm=the oxygen content of the combustion air supplied, % by vol; in most cases is put at 21 ; [CO2]=the carbon dioxide content of the waste gases, ,/n by vol; [CO2]max=the maximum possible value of the carbon dioxide content of the flue gases, //n by vol; for the fuel used in the heating appliance, i.e. the value holding at stoichiometric quantity of the air supplied and for complete combustion.
By means of the above equations the scale can be divided in relation to the oxygen or carbon dioxide content to be measured.
Instead of the 'air excess' the scale division may show the co-called 'air factor', herein defined as a quantity L satisfying: Q L= Qmin) in which -Qimin) Q=the quantity of combustion air supplied; Qm,n1=the minimum quantity of combustion air required for stoichiometric combustion.
The 'air factor' can also be calculated from the measured oxygen or carbon dioxide content. However, preference is given to the use of the 'air excess' as defined above.
The invention will be elucidated with reference to the drawing, by way of nonrestrictive example. The figures show: Fig. 1: a preferred division of the dial of apparatus according to the invention with pointers indicating the efficiency rating as good"; Fig. 2: the dial of Fig. 1 with pointers indicating the efficiency rating as 'moderate'.
The dial according to Fig. I has a temperature scale for the chimney temperature and a scale on which the air excess derived from the quality of the waste gases is indicated (in this case the derivation is from the CO2 content). A is the centre of rotation of the pointer for the chimney temperature. and B is the centre of rotation of the pointer for the percentage air excess.
The dial is further provided with diagram lines 1, 2 and 3, forming the edges of the areas I--IV indicating good, fair, moderate and poor efficiency as calculated for Groningen natural gas (composition substantially 81.3 " CH4, 14.35 " N2 and 0.89"" CO2) by means of the equation applicable to this gas and known per se: 0.34 7p90-(+0.0076)(Tt).
[CO2] Roughly, the following efficiency values are applied if this gas is fired: GOOD q > 82.5 n FAIR 71 between 78 and 82.50,, MODERATE 77 between 72 and 780 POOR In Figs. 1 and 2, the numeral 4 indicates the temperature pointer and 5 the air-excess pointer, with the point of intersection lying within the area of 'good' efficiency in Fig. 1 and within the area of 'moderate' efficiency in Fig. 2. An important point is that thanks to the temperature and air excess being presented separately, an immediate indication is obtained for efficiency improvement should this be desirable.
It will be clear that. if the measuring instruments for temperature and/or air excess have a scale indication slightly different from that shown in the figures, the position of the diagram lines 1,2 and 3 will be different, too.
Although the preferred design of the dial according to Fig. I and 2 is meant specifically for determining the efficiency of heating appliances firing Groningen natural gas, other gas compositions not differing too much will have only a minor influence on the position of the diagram lines.
The invention is not restricted to the example here given. Thus the diagram lines may be drawn to correspond to quite different efficiency values than indicated above, the number of areas need not be four, or for a fuel other than natural gas the diagram lines will be differently positioned.
In instances where an efficiency measuring instrument according to the invention is to be used for several types of fuel. the dial is made exchangeable, so that a dial with the correct scale division can be mounted for each type of fuel.
The apparatus may be constructed in a simple and cheap way by taking an existing oxygen or carbon dioxide meter and adding a unit for measuring temperature. In order to obtain a temperature measurement of high accuracy. sampling and temperature measurement are combined in a so-called exhaust pyrometer. The waste gases to be analyzed are aspirated into the exhaust pyrometer past the thermo-element. This makes for a good heat transfer between waste gases and thermo-element, resulting in an accurate temperature measurement.
This temperature measurement is combined with the measurement of O2 or CO2; the measured O2 or CO2 content can be expressed in the air excess.
WHAT WE CLAIM ISt 1. Apparatus for indicating the efficiency of a heating appliance, which apparatus comprises two measuring instruments for generating electrical signals in response to the flue temperature, and to the carbon dioxide content of the flue gases or the oxygen content of the flue gases as a function of the oxygen content of the combustion gases supplied, respectivelv.
and the said signals each effect a corresponding swing to a respective indicator arm of a pair of intersecting indicator arms and a dial calibrated into a plurality of areas each corresponding to an indicated degree of efficiency, whereby the point of intersection of the said indicator arms when viewed in conjunction with the said dial provides an indication of the efficiency of the said heating appliance under operating conditions.
2. Apparatus as claimed in Claim 1, wherein one of the said measuring instruments is an instrument operative in response to the carbon dioxide content of the flue gases, and the said dial of the apparatus according to the invention is characterized by diagram lines indicating constant efficiency for efficiency values not differing by more than an amount of 2% from 82.5In, 780; and 72% as calculated from the equation
in which 77=operating efficiency at complete combustion; [CO2]=the carbon dioxide content of the flue gases, 0: :, by vol; T=the temperature of the flue gases, OC; t=the temperature of the combustion air supplied, OC; b, c and d=constants whose values
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. The dial according to Fig. I has a temperature scale for the chimney temperature and a scale on which the air excess derived from the quality of the waste gases is indicated (in this case the derivation is from the CO2 content). A is the centre of rotation of the pointer for the chimney temperature. and B is the centre of rotation of the pointer for the percentage air excess. The dial is further provided with diagram lines 1, 2 and 3, forming the edges of the areas I--IV indicating good, fair, moderate and poor efficiency as calculated for Groningen natural gas (composition substantially 81.3 " CH4, 14.35 " N2 and 0.89"" CO2) by means of the equation applicable to this gas and known per se: 0.34 7p90-(+0.0076)(Tt). [CO2] Roughly, the following efficiency values are applied if this gas is fired: GOOD q > 82.5 n FAIR 71 between 78 and 82.50,, MODERATE 77 between 72 and 780 POOR In Figs. 1 and 2, the numeral 4 indicates the temperature pointer and 5 the air-excess pointer, with the point of intersection lying within the area of 'good' efficiency in Fig. 1 and within the area of 'moderate' efficiency in Fig. 2. An important point is that thanks to the temperature and air excess being presented separately, an immediate indication is obtained for efficiency improvement should this be desirable. It will be clear that. if the measuring instruments for temperature and/or air excess have a scale indication slightly different from that shown in the figures, the position of the diagram lines 1,2 and 3 will be different, too. Although the preferred design of the dial according to Fig. I and 2 is meant specifically for determining the efficiency of heating appliances firing Groningen natural gas, other gas compositions not differing too much will have only a minor influence on the position of the diagram lines. The invention is not restricted to the example here given. Thus the diagram lines may be drawn to correspond to quite different efficiency values than indicated above, the number of areas need not be four, or for a fuel other than natural gas the diagram lines will be differently positioned. In instances where an efficiency measuring instrument according to the invention is to be used for several types of fuel. the dial is made exchangeable, so that a dial with the correct scale division can be mounted for each type of fuel. The apparatus may be constructed in a simple and cheap way by taking an existing oxygen or carbon dioxide meter and adding a unit for measuring temperature. In order to obtain a temperature measurement of high accuracy. sampling and temperature measurement are combined in a so-called exhaust pyrometer. The waste gases to be analyzed are aspirated into the exhaust pyrometer past the thermo-element. This makes for a good heat transfer between waste gases and thermo-element, resulting in an accurate temperature measurement. This temperature measurement is combined with the measurement of O2 or CO2; the measured O2 or CO2 content can be expressed in the air excess. WHAT WE CLAIM ISt
1. Apparatus for indicating the efficiency of a heating appliance, which apparatus comprises two measuring instruments for generating electrical signals in response to the flue temperature, and to the carbon dioxide content of the flue gases or the oxygen content of the flue gases as a function of the oxygen content of the combustion gases supplied, respectivelv.
and the said signals each effect a corresponding swing to a respective indicator arm of a pair of intersecting indicator arms and a dial calibrated into a plurality of areas each corresponding to an indicated degree of efficiency, whereby the point of intersection of the said indicator arms when viewed in conjunction with the said dial provides an indication of the efficiency of the said heating appliance under operating conditions.
2. Apparatus as claimed in Claim 1, wherein one of the said measuring instruments is an instrument operative in response to the carbon dioxide content of the flue gases, and the said dial of the apparatus according to the invention is characterized by diagram lines indicating constant efficiency for efficiency values not differing by more than an amount of 2% from 82.5In, 780; and 72% as calculated from the equation
in which 77=operating efficiency at complete combustion; [CO2]=the carbon dioxide content of the flue gases, 0:, by vol; T=the temperature of the flue gases, OC; t=the temperature of the combustion air supplied, OC; b, c and d=constants whose values
depend on the fuel used in the said heating appliance and do not differ by more than 100, from the following values: b=0. 34 c=0.0076 d=90.
3. Apparatus according to Claim 1, wherein one of the said measuring instruments is an instrument operative in response to the oxygen content of the flue gases, and the said dial of the apparatus is characterized by diagram lines indicating constant efficiency for efficiency values not differing by an amount of more than 2% from 82.5 ,'n, 78 and 72% as calculated from the equation::
in which rl, T, t, d and c have the same meanings as set forth in Claim 2, and [O2]=the oxygen content of the flue gases, by by vol; [O21atm=the oxygen content of the combustion air supplied, % by vol; a=a constant the value of which depends on the fuel used in the heating appliance and does not differ by more than 100/, from the value a=0.78.
4. Apparatus according to any of Claims I to 3, wherein the said indicator arm which is connected with the measuring means for flue temperature registers with a scale on the said dial calibrated for flue temperature.
5. Apparatus according to any of Claims I to 4, wherein the said indicator arm connected with the said measuring means of the carbon dioxide or oxygen content of the flue gases registers with a scale on the said dial calibrated for air excess as hereinbefore defined.
6. Apparatus according to any of Claims I to 4, wherein the said indicator arm connected with the said measuring means of the carbon dioxide or oxygen content of the flue gases registers with a scale on the said dial calibrated for air factor as hereinbefore defined.
7. Apparatus according to any of Claims 1 to 6, wherein the said dial is exchangeable.
8. Apparatus according to any of Claims I to 7, which includes an exhaust pyrometer for determining the flue gas temperature T.
9. Apparatus according to Claim 8, wherein the said exhaust pyrometer also serves for aspirating sample gas for the determination of [CO2] or [021.
10. Apparatus according to Claim 1, substantially as hereinbefore described, with particular reference to the accompanying drawing.
GB5054977A 1976-12-08 1977-12-05 Apparatus for determining the efficiency of a heating appliance Expired GB1561020A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7613621A NL7613621A (en) 1976-12-08 1976-12-08 DEVICE FOR DETERMINING THE EFFICIENCY OF A STOVE.

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GB1561020A true GB1561020A (en) 1980-02-13

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GB5054977A Expired GB1561020A (en) 1976-12-08 1977-12-05 Apparatus for determining the efficiency of a heating appliance

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DE (1) DE2753498A1 (en)
FR (1) FR2373778A1 (en)
GB (1) GB1561020A (en)
NL (1) NL7613621A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4423487A (en) * 1979-11-23 1983-12-27 Neotronics Limited Apparatus for measuring the efficiency of combustion appliances
DE3331706A1 (en) * 1983-09-02 1985-04-04 Wilfried 7705 Steißlingen Beck Process and device for accepting or recording measuring data of a heating installation
US4685072A (en) * 1981-12-10 1987-08-04 The Babcock & Wilcox Company Steam generator on-line efficiency monitor
CN103743434A (en) * 2013-12-20 2014-04-23 广州广电计量检测股份有限公司 Electric-hot-plate calibration method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH670149A5 (en) * 1985-10-28 1989-05-12 Landis & Gyr Ag

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR988222A (en) * 1948-12-14 1951-08-24 Mernoki Vallalkozasok K F T Operational control system for industrial installations
US3214975A (en) * 1963-06-05 1965-11-02 Edward G Solecki Temperature humidity index measuring instrument
CH418358A (en) * 1963-08-12 1966-08-15 Licentia Gmbh Display device for the operating status of heat engines, preferably steam turbines

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4423487A (en) * 1979-11-23 1983-12-27 Neotronics Limited Apparatus for measuring the efficiency of combustion appliances
US4685072A (en) * 1981-12-10 1987-08-04 The Babcock & Wilcox Company Steam generator on-line efficiency monitor
DE3331706A1 (en) * 1983-09-02 1985-04-04 Wilfried 7705 Steißlingen Beck Process and device for accepting or recording measuring data of a heating installation
CN103743434A (en) * 2013-12-20 2014-04-23 广州广电计量检测股份有限公司 Electric-hot-plate calibration method
CN103743434B (en) * 2013-12-20 2016-04-13 广州广电计量检测股份有限公司 Electric-hot-plate calibration method

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Publication number Publication date
DE2753498A1 (en) 1978-06-15
FR2373778A1 (en) 1978-07-07
NL7613621A (en) 1978-06-12

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