Reviews of the Lenoir gas engine
Prices of Lenoir machines in 1860
| Power | Delivered and installed in Paris | Delivered and installed in the departments of France | |||
|---|---|---|---|---|---|
| 1/2 horse power | 900 Fr. | 1,100 Fr. | |||
| 1 horse power | 1,350 Fr. | 1,500 Fr. | |||
| 2 horse power | 1,910 Fr. | 2,110 Fr. | |||
| 3 horse power | 2,470 Fr. | 2,670 Fr. | |||
| 4 horse power | 3,030 Fr. | 3,230 Fr. | |||
| 6 horse power | 4,200 Fr. | 4,500 Fr. | |||
| 8 horse power | 5,370 Fr. | 5,720 Fr. | |||
| 10 horse power | 6,540 Fr. | 6,940 Fr. | |||
| 12 horse power | 7,760 Fr. | 8,110 Fr. | |||
| 15 horse power | 9,490 Fr. | 9,990 Fr. | |||
| 20 horse power | 11,930 Fr. | 12,630 Fr. |
source: Polytechnisches Journal, Vol. 159, pages 75-76
1861
The Lenoir gas engine attracted wide attention and was subject of various in-depth investigations in France and abroad:
The power is provided by illumination gas (caol gas), which at a price of 30 centimes for a cubic meter is still expansive and not available at all in the country side, where Lenoirs engine shall provide useful services. Without doubt, with an increased spread of the gas engines alternative sources based on amyles, naphta ect. should become available.
The manufacturer, M. Marinoni found out that the consumption should not be more than 1 cubic meter per hour and horse power. Usual steam engines with an output power of one horse power require scarcely less than 5 kg of coal per hour which cost about 20 centimes. By including all other costs the Lenoir engine is economic at the current price of illumination gas, as no boilerman is needed.
The first machine for practical application was delivered on 29 September 1860 to Mr. Barvajel, a manufacturer of gold braids, ropes and ornamental trimmings. This 1 horsepower machine replaces two workers, which had to turn two big wheels for 10 hours a day. These two workers cost 6 francs, the machine only 3 francs, and is working much smoother.
A Mr. Hirn provided some calculations based on a supply of 10% illumination gas and 90% of air. The pressure [in the cylinder] did not exceed 6 atmospheres. Even with only 7.5% of illumination gas, the usual mixture, the Lenoir engine was better than any steam engine. He stated that the Lenoir engine did not cause any explosions.
source: "Cosmos, revue encyclopedique hebdomadaire des progres des sciences. Vol. 17, 1860, "Moteur à air dilaté ou machine à gaz de M. Lenoir," pages 610-628
According to this article the running costs for a Lenoir gas machine was just 1.5 times higher than that for a comparable steam engine. However, as we learn below the data given on the efficiency of their gas machine was a disinformation on the part of the vendor, as the real consumption was as high as 2.6 cubic meter per horse power and hour. That made the fuel costs of the Lenoir gas machine 4 times higher than a steam engine.
Doubts about the usefulness of Lenoir's gas machine urged Dr. Heinrich Schwarz to conduct some experiments.
When the machine runs at low speed it consumes in relation to the produced power relatively plenty of gas, per horsepower and hour about 2.6 cubic meter of gas. The efficiency improves at a higher speed, but then the machine is suffering from vibrations and does not need a boiler man but an oiler man to counter friction an gas losses. New experiments with a Lenoir machine specified as 4 horse power gave results of 2.82, 2.54 and 2.36 horse power at speeds between 110 - 125 rounds per minute. For the latter test the machine was consuming 1695 liter of gas per horse power and hour. For the gas machine specified as 2 horse power, the machine delivered 0.67 horse power at 136.6 rpm and 1.21 horse power at 173.7 rpm. The consumption with 1645 liter per horsepower and hour was similar. The costs of a steam engine with comparable power is one fith of the costs of the Lenoir engine. Due to these experiments the prospects of Mr. Lenoir to sell his machine to Spain were destroyed by these experiments.
Dr. Heinrich Schwarz, "Uber Lenoir's Gasmaschine"; Breslauer Gewerbeblatt 26 January 1861, Nr. 2; reprinted in Polytechnical Journal Vol. 159, 1861, pages 165-172.
However, we have to take into account that the prices taken into account were the prices in Breslau in the historical region of Silesia, today Poland. It may be that the prices for illumination gas in Paris, where illumination gas was widely used, might have been lower in comparison to coal than in Breslau. From other authors we learn that in Paris at the time the running costs for a Lenoir engine were only twice of that of a comparable steam engine.
By 1861 about 30 Lenoir gas machines were in operation in Paris with an output power between 1 and 8 horse power, which was taken as a confirmation that they were sufficiently developed.
Even the lubrication has been improved as now little devices are now atomically oiling the machine during its operation. The supply of illumination gas and water does not seem to be a problem in Paris. The costs for private use of water is 70 to 80 Francs a year for a minimum consumption of 1 cubic meter per day. (this makes it about 20 - 22 centimes per day and cubic meter). As the water is only heated, it may be still re-used for other purposes.
Although the consumption is believed to be around 1 cubic meter of illumination gas per horse and hour, measurements are showing a consumption of 2,7 - 2.8 cubic meter per horse and hour, which corresponds to at a price of 30 centime per cubic meter illumination gas to 81 - 84 centime per horse and hour.
According to their price list the manufacturer Lenoir had delivered by the end of June 1861 39 machines in Paris, 17 machines in the rest of France and 16 machines abroad, it total 72 machines.
source: Prof. E. G. Schmidt in Stuttgart, "Die Gasmaschinen in Paris", Dingler's Polytechnisches Journal. Band 162, Seiten 233-235.
Thankfully the author let us know that 0.5 liter beer in Paris cost 40 centimes, whereas a worker to push machines manually is 30 centimes per hour (3 Francs for a 10 hour working day). Despite the lower running costs of a steam engine Prof. Schmidt believes that in cities the Lenoir gas machine has a great future, all the more he expects that the efficiency will be improved over the coming years.
Chemical composition of illuminating gas
Gustav Schmidt tried to calculate the consumption of the Lenoir gas machine. We have to understand that thermodynamics was in its infancy and his calculations method is not up to todays scientific knowledge. He also gives some background information of the chemical composition of illuminating gas produced in Vienna.
| Chemical substance* | Chemical formula | parts by Volume | specifc weight | weight | Modern analysis ** |
|---|---|---|---|---|---|
| oil forming gas (ethylen) | C2H4 | 8 | 0.967 | 7.736 | minimal ** |
| swamp gas (methan) | CH4 | 35 | 0.559 | 19.565 | 21 |
| hydrogen | H2 | 46 | 0.0651 | 3.179 | 51 |
| carbonoxid (carbon monoxide) | CO | 7 | 0.9678 | 6.775 | 9 |
| nitrogen | N2 | 3 | 0.9713 | 2.194 | 15 |
| carbon acid (carbon dioxide) | CO2 | 1 | 1.529 | 1.529 | minimal |
| total | 100 | 41.698 | minimal |
* The table shows the name of the gases at the time and the today's name in parenthesis if it differs.
** More accurate Analysis by the Vienna gas plant
*** Other sources indicate 5% o ethylen = C2H4
The specific density of the Vienna illuminating gas was therefore 0.417 kg/m3. The heating value was 11,400 kcal/kg (47.730 MJ/kg).
In Vienna the 100 cubic feet of illuminating gas cost 48 Neukreuzer. Even if it is difficult to transform Neukreuzer into French Francs, we are given the relation between the fuel costs for a 2 horse power Lenoir gas machine and a steam machine. The consumption per horse power and hour for a Lenoir gas machine was 24 Kreuzer and the fuel cost for coal for a steam engine was 8-10 Kreuzer per horse power and hour. This means that, similar to Paris, the Lenoir gas machine was 2.4 - 3.0 times more expansive with respect to the fuel cost.
Gustav Schmidt, "Theorie der Lenoirschen Gasmaschine", Zeitschrift des Österreichischen Ingenieursvereins, Heft IV and V, S. 85; reprinted in Dingler's Polytechnisches Journal, 1861, Band 160, S. 321.
Heating values
Let's compare the relative costs for heating values:
| fuel | Heating value MJ/kg | costs per kg | cost per kJ |
|---|---|---|---|
| coal | 24 | 0.025 | 1.0 |
| illuminating gas | 47 | 0.60 | 12.7 |
| petroleum | 42 | 0.33 | 7.9 |
| ligroine | 41 | 0.62 | 15.1 |
The costs are calculated on basis of Mark. As the carburetor in our todays understanding was not yet invented, white spirit and lingroin were used as liquid fuel, as they had a lower boiling point, allowing for evaporating it. The names are not identical with today's name and even at the time were used interchangable for different products (Gasolin, Ligroin, Ligroine, Naphta, Naphtha, Nafta, Petroleumäther, ...). Therefore we should rather compare it with their boiling point or the specific weight. Surgical spirit (Fleckwasser, Waschbenzin) had a specific weight of 0.680 - 0.700 kg/l and a boiling point around 80° and got his name as it is a solvent for the adhesive of adhesive bandages. Ligroin having a specific weight of 0.710 - 0.730 substituted in special lamps whale oil and saved so many lives of the whales. It was mostly sold in pharmacies, also for cleaning clothes.
In addition to the problem of the names being used confusingly, before the reunification of Germany in the Imperial Germany (Kaiserreich), different currencies existed in different parts of Germany. From a source in 1868 the price for 50kg of ligroin was 18 Gulden which can be converted into 0,62 Mark per kg (1 Mark = 7/12 Gulden).
G. Lieckfield's handbook "Die Petroleum und Benzinmotoren, ihre Entwicklung, Konstruktion und Anwendung" from 1894 states on p. 3 that surgical spirit cost without taxes 16.75 Mark per 100 kg. This is already about one quarter of the price one had to pay 28 years before. We should be jealous about the price, as liquid fuel with a specific density of less thean 0.79 kg/l for the purpose of running machines was not taxed. Thus in 1894 the running costs for "gasoline"-engines with a consumption of now only 0.6l or 0.42 kg per horsepower and hour (Lieckfield, page 9) were now less than the running costs for gas machines running with 0.8 cubic meter of town gas/illuminating gas per horse power and hour.
The price of 1 cubic meter of illuminating gas was calculated based on the specific density of 0.417 kg/m3.
Efficiency
When we want to compare the efficiency of a steam engine and the Lenoir gas engine we have to take into account that 1 horse power was define in central Europe as 75 kg per meter per second. This is equivalent to 735.5 Watt/second. The work produced in 1 hour of a 1 horse power machine is therefore equivalent 735.5 times 3600 seconds = 2.65 MJ. We can compare therefore the efficiencies of a steam engine and the Lenoir gas engine by using the fuel input
| type of engine | fuel | fuel used for 1 horse power and 1 hour | Heating value of fuel | efficiency |
|---|---|---|---|---|
| small steam engine without condensator | coal | 5 kg | 24 MJ/kg | 2.25% |
| Lenoir gas engine | illuminating gas | 1.2 kg | 42 MJ/kg | 5.2% |
Even if the specific energy costs of illuminating gas was 12 times higher than coal, the Lenoir engine could make up to a great extend for this disadvantage as it was more efficient. The efficiency of big steam engines with a condensator was at the time around 8%. However, the efficiency of a 1 horse power steam engine was considerably lower, also due to relative higher heat losses of the boiler. Most of the higher efficiency of the Lenoir engine probably is due to the effect of internal combustion which avoids heat losses outside of the gas engine.
1862
In a test conducted over a time of 1 hour and 50 minutes a Lenoir gas machine delivered at 47rpm a power of 1.85 horse powers. At a mixture of 1 part illumination gas to 12 part of air the machine consumed 2,712 liter illumination gas per horse power per hour. Due to the diluted gas mixture the machine during this test run stopped three times. In another test the charge was reduced so that the same machine delivered only 1,42 horse power which reduced the explosion noise but increased the specific consumption to 3,435 liters per horse power per hour. Measurements showed that the pressure in the cylinder was highly fluctuating with a maximum pressure was 6 atmospheres. As the pressure at the end of a piston stroke was higher than the atmospheric pressure, which explains the shocks produced by the machine. This suggests that the exhaust openings are still not sufficiently large.
In a later test for the duration of 1 hour and 30 minutes an improved model with a stroke of 300mm and a piston diameter of 160mm delivered 1,02 horse power at 81 rpm. The consumption was 2,878 liter per horsepower and hour. An analysis of the illumination gas used for the last test showed that for a complete combustion the mixture of illumination gas to air should be 0.13 to 1.0 (or 1 : 7.7). This last test was however run with a mixture of 0.077 : 1.0 (or 1 : 13) which reduced the generated heat and guaranteed a smoother run.
The machine used per hour 800 liter of cooling water which entered the machine at 18°C and left the machine at 40°C.
The temperature of the exhaust gas was 280°C. The exhaustion gases were also chemically analysed and the following result were obtained:
| Chemical element | Volume |
|---|---|
| Oxygen | 2.89% |
| Carbon Dioxide | 8.18% |
| Hydrocarbons | 1.17% |
| Hydrogen | 1.72 |
| Nitrogen | 86.04% |
| total | 100.0% |
Each combusted 1000 liter of illumination gas also generated 1.256 kg of water vapour. 1kg of condensed water comprised:
| Nitric acid | 0.022g |
| Ammonia | 0.106g |
| Ferric Oxide | 0.612g |
| Sulfuric acid | 0.305g |
The original analysis gave the amount of acid for 6.26 kg of condensed water, which corresponds to the emission of a 2 horse power machine over an hour. I recalculated these figures for an emission of 1 kg.
A comparison of the calorific value of coal times for the amount of coal used by a steam engine of the same power with the calorific value of illumination gas times the amount of consumed illumination gas showed that the Lenoir gas engine is 1.9 times less efficient as a steam engine.
The costs for the zinc-sulfuric acid battery, that is used for the ignition spark was calculated to be 3 centimes per hour.
The consumption of lubrification oil was calculated to 36.5g per operation hour, which is about 10 centimes per hour. If the machine was not oiled a speed reduction was observed already after 15 minutes.
The alternating switching of the gas supply caused changes in the gas pressure in the supply lines which extinct flames closer than 10m, and only smoothed out after 100m. However with a rubber bag of 20 liter volume as a buffer this problem could easily be solved.
"Tresca's Bericht über Versuche mit der Lenoirschen Gasmaschine"; in Dingler's Polytechnischem Journal Band 163, 1862, pages 162-171.