Turbocharged Zhou Engine

(Updated on 2022-05-08)

This article introduces the some unique features of Zhou Engine, reveals how to realize the real thermal efficiency more than 0.6, how to recover full the exhaust pressure of Zhou Engine rather than the waste heat, better exhaust purification, and is trying to make one big breakthrough in the current theory of internal-combustion (IC) engines.

Zhou Engine is an internal-combustion (IC) engine also a combustor of a gas turbine, which patent number is PCT/CA2014050106. The video (or in China https://v.youku.com/v_show/id_XMTUyMTQ4MTQ4OA==.html?from=s1.8-1-1.2) shows the working cycles of single piston of Zhou Engine and the toothed-rollers' motion. (This cycle has many differences with the Atkinson cycle, shown in the following.) The patent file is at https://patentscope.wipo.int/search/docservicepdf_pct/id00000030299621/APBDY/WO2015120530.pdf.

The plurality pistons of a Zhou Engine are driven by one power-cam. We can crafty design a "specific piston motion curve”, which can be actualized by the power-cam, to make each piston motion mutual complement, to avoid the pulsation in the total flow of the intake and the exhaust, to fit optimally an aerodynamic compressor and a turbine. As a result, we will obtain an engine with more thermal efficiency (to 0.74 ideally) and higher specific power.

Fig.1 is the specific piston motion curve, and then we design a power-cam in fig. 2 according the fig.1, to actualize the fig.1. Note, this piston motion curve and power-cam are different from that in the video above. Then we design a Zhou Engine (say “this Zhou Engine” below) with six pairs of pistons in fig.3.

(Note: For easily showing the principles, here shows a radial Zhou Engine in fig. 3, the details of a radial Zhou Engine show in the fig. 3~8 of the patent file. If you want to manufacture a Zhou Engine, please select one with barrel type, or seeing the fig. 9~13 of the patent file, which is very compact and higher specific power.)

For easy description, we use the following symbols in table 1, in the following expressions.

Because this Zhou Engine has six piston pairs that arrange evenly around the power-cam, the phase difference between its neighbouring piston pairs is C/6, naturally.

§1. Toothed-roller

A toothed-roller (seeing the detail H of fig.3), it is one of the keys of Zhou Engine. Using of it avoid almost all the friction in a conventional cam mechanism, and break through the limit of using a conventional cam. Using of it, a cam can drive a follower also a follower can drive a cam, with high mechanical efficiency.

The toothed-rollers are shown in fig.3. The Detail H of fig. 3 shows the engaging of toothed-rollers and the shell and the piston. The lateral force of the piston, which comes from the power-cam, acts on the shell through the toothed-rollers, rather than acting on the cylinder wall, to avoid the huge friction between the piston and cylinder of a conventional engine.

In a conventional piston engine, the lateral force of its piston that comes from the link rod, acts on the cylinder wall, leads to the huge friction between the piston and cylinder. 1) The huge friction consumes a lot of mechanical work, which is about the 20% of the engine output. 2) The huge friction limits piston motion speed (if over the limit, the cylinder wall or piston ring would burn up), and then limits the engine’s rotating speed, and then limits the raising of its specific power.

The operating principle of the toothed-rollers is that: A conventional roller bearing, the rolling orbit is a ring surface. Even if the rollers slide, the rollers are in the appropriate position and work well. Therefore, we need not prevent the rollers from sliding. However, in a Zhou Engine, the rolling orbit is a plane. If the rollers slide, the rollers may get away from the appropriate position and fail to work. Therefore, we must prevent the rollers from sliding. Therefore, we fix a gear rack on the edge of a rolling orbit, fix a gear wheel on one end of each roller to form toothed-rollers and mesh their teeth. Then, the toothed-rollers cannot slide and can only roll. If the design and manufacturing are good, the force that acts on the gear rack and gear wheel is tiny, equals the inertia force of the toothed-rollers in seldom time, and equals zero usually. Therefore, the engagement of the gear rack and gear wheel hardly affects mechanical efficiency.

For sealing between the piston and cylinder, the piston ring has slightly expansive force that acts on the cylinder wall. The expansive force leads minor friction between the piston and cylinder in a conventional engine, which cannot be avoided by the toothed-rollers.

For more detail on toothed-rollers, please read the post "Power-cam mechanism" and the patent file.

To avoid harmful inertial thinking of cam mechanism, please see “A Typical Style of Thinking” (https://www.dhirubhai.net/pulse/typical-style-thinking-jing-yuan-zhou ).

Because of the using of toothed-rollers, we can use the power-cam to drive the pistons according to the specific piston motion curve and obtain high mechanical efficiency. Otherwise, if we use a conventional cam to drive the pistons according to the specific piston motion curve, the benefits of thermodynamics will be wasted by the sliding friction and low mechanical efficiency of the conventional cam; the optimized piston motion will lose meaning.

Therefore, the using of toothed-rollers is one of the keys of Zhou Engine.

The purpose of the power-cam mechanism and toothed-roller array is far broader than on Zhou Engine.

§2. The total intake flow has no pulsation

The intake stroke of this Zhou Engine takes C/4, and is divided into three curve segments, s1(t), s2(t), s3(t), shown in the fig.1 and the following expression (1).

Seeing the following fig. 4, when this piston pair suctions air along s1(t) and t∈[0, C/12], the previous piston pair suctions air along s3(t) and t∈[2*C/12, 3*C/12], their phase difference is C/6, the others are not in intake stroke. So the total intake volume flow rate F(t) is in expression (2).

When this piston pair suctions air along s2(t) and t∈[C/12, 2*C/12], it suctions alone, the others are not in intake stroke, so the total intake volume flow rate F(t) is in expression (3).

When this piston pair suctions air along s3(t) and t∈[2*C/12, 3*C/12], the next piston pair suctions air along s1(t) and t∈[0, C/12], they are equals — we turn our viewpoint on the next piston pair and repeat the process of expression (2).

If we keep changing our viewpoint as the power-cam rotates, the F(t) will keep repeating and alternating the processes of expression (2) and (3). So that, the F(t) keeps a constant A*900/C. Thus, this Zhou Engine has no pulse in its total intake flow.

§3. The total exhaust flow has no pulsation

The exhaust stroke of this Zhou Engine takes C/4, and is divided into three curve segments, e1(t), e2(t), e3(t), shown in the fig.1 and the following expression (4).

Imitating the deducing process of §2 above.

When this piston pair exhausts along e1(t) and t∈[9*C/12, 10*C/12], the previous piston pair exhausts along e3(t) and t∈[11*C/12, C], their phase difference is C/6, the others are not in exhaust stroke, so the total exhaust volume flow rate F(t) is in expression (5).

When this piston pair exhausts along e2(t) and t∈[10*C/12, 11*C/12], it exhausts alone, the others are not in exhaust stroke, so the total exhaust volume flow rate F(t) is in expression (6);

When this piston pair exhausts along e3(t) and t∈[11*C/12, C], the next piston pair exhausts along e1(t) and t∈[9*C/12, 10*C/12], they are equals — we turn our viewport on the next piston pair and repeat the process of expression (5).

If we keep changing our viewport as the power-cam rotating, the F(t) will keep repeating and alternating the processes of expression (5) and (6). So that, the F(t) keeps a constant –A*900/C. Thus, this Zhou Engine drives a constant volume flow rate on its total exhaust flow.

If we keep the gas pressure of this total exhaust outlet equaling the gas pressure of the end of the expansion stroke of this Zhou Engine, shown at the point E in fig.1, then this total exhaust flow will keep in a constant flow and have no pulse. If we use this total exhaust flow to drive a turbine, seeing fig.6, we can adjust the adjustable vanes of the turbine to keep the gas pressure (point E, p=1.5). Thus, this total exhaust flows to the turbine is steady, has no pulse, and has no isenthalpic expansion. The following is our selected working condition, seeing fig.5 and 6.

§4. PV-diagram

The pV diagram of fig.5 describes the relationship between the pressure and the volume of the working substance in one thermodynamic working cycle, of this turbocharged Zhou Engine. A pV diagram is commonly used for thermodynamic analysis of a general hot engine.

The parameters of point A, B, C, D, E, F and G are consistent in fig.1, 5, 6 and 8.

Here, we draw a pV-diagram in fig.5, which shows full use of the mechanical energy in one thermodynamic cycle, of this turbocharged Zhou Engine. The working substance is air, its adiabatic index is 1.4. We start at point A (p=0.1013, V=V1, T=273.15), suction into air. Then the working substance adiabatic compresses to point B (p=6.715, V=0.05*V1, T=905.3), along the equation p*V^1.4=0.1013*V1^1.4, this process absorbs energy. Then combusting, the working substance is heated and gets to point C (p=18.544, V=0.05*V1, T=2500), along the equation V=0.05*V1, and is injected heat 1.4795*V1 (MJ). Then the working gas adiabatic expand sufficiently and gets point D (p=0.1013, V=2.0658*V1, T=564.28), along the equation p*V^1.4=0.2797*V1^1.4 . Then the working gas discharges to atmosphere at point D.

We choose the point E (p=1.5, V=0.3013*V1, T=1218.8) on the curve C-D, and the point F (p=0.5433, V=0.3013*V1, T=441.4) on the curve A-B. We realize the loop F-B-C-E-F in this Zhou Engine, realize the process A-F in the aerodynamic compressor, and realize the process E-D in the turbine, seeing fig.6.

How should we understand the parameters in fig.5? If the volumes of intake and exhaust of this Zhou Engine are both 301.3cc (corresponding to point F, F respectively), then it real suctions 1000cc air in each cycle (point A), and exhausts 2065.8cc in each cycle (point D). The parameters of point B and C take place inside this Zhou Engine. In this turbocharged Zhou Engine, the volume of its suction is V1/(0.3013*V1)=3.3 times of its cylinder internal volume, or say, its real displacement is 3.3 times of its cylinder displacement; however, now, a turbocharged conventional engine, its highest real displacement is 1.4 times of its cylinder displacement.

How do we select the points E and F of fig.5? First, we select the temperature (T=1218.8K) of point E, that is the highest temperature can be withstood in curve C-D, according to the turbine, pipe, and the catalytic exhaust purifier; then calculate the gas pressure (p=1.5), the volume (V=0.3013*V1) of point E. Second, we select a volume (V=0.3013*V1) of point F in curve A-B, that equals the volume of point E, then calculate the gas pressure (p=0.5433), the temperature (T=441.4K) of point F. So that, this cylinder volume at point E is the minimum of this Zhou Engine needed, and we fully utilize this cylinder volume to compress the air. Since, the adiabatic mechanical efficiency of a piston compressor is higher than an aerodynamic compressor.

Thus, we match optimally this Zhou Engine, the aerodynamic compressor and the turbine, shown in fig.5 and 6.

Seeing fig.5, the output work is the area of A-F-B-C-E-D-A and equals to 1.1015*V1(MJ); the heat injected from curve B-C is 1.4795*V1(MJ); then this ideal thermal efficiency =1.1015/1.4795=0.74. This calculation has deducted the transport work of the exhaust. This ideal thermal efficiency is less than that of Carnot cycle, but is higher than that of all other hot engines. For the transport work, please read “A common mistake in textbooks of physics” (https://lnkd.in/gdvvrYT ). The estimated actual thermal efficiency of this turbocharged Zhou Engine will reach 0.6 or higher.

If we add interstage cooling inside the aerodynamic compressor, we will obtain higher thermal efficiency, and the thermal efficiency will be nearer the Carnot cycle.

Fig.6, the turbocharged Zhou Engine and their parameters, is also a gas turbine with a combustor of Zhou Engine and their parameters matching.

The T-S diagram of this turbocharged Zhou Engine is in the §3 of "A Common Mistake in the Current Thermodynamics of IC Engines".

§5. Comparing with a turbocharged conventional engine

Fig.7 shows a typical pV-diagram of a turbocharged conventional engine, which is schematic. The total flows of intake and exhaust of a conventional engine both have huge pulsation. The gas flow from the aerodynamic compressor to the conventional engine has isenthalpic expansions, shown in curve 8-1; the gas flows from the conventional engine to the turbine has isenthalpic expansion, shown in curve 4-5. The isenthalpic expansions of 8-1 and 4-5 lose a lot of mechanical energy, that is the most different from fig.5.

Each cylinder of a conventional IC engine has big enough clearance volume and residual exhaust gas contained, and the intake valve open period overlaps a part of the exhaust valve open period. If the ending pressure of the exhaust stroke higher than the pressure of the intake gas, the intake gas will be limited, even be impeded and then stop the IC engine. Thus, in fig.7, the gas pressure of driving the turbine cannot be greater than the intake gas pressure Pk, then the isenthalpic expansion 4-5 is inevitable.

Whereas, each cylinder of a Zhou Engine has little clearance volume and little exhaust gas contained, and the intake valve open period does not overlap the exhaust valve open period. This Zhou Engine's exhaust pressure does not affect its intake gas, thus, its exhaust pressure can be fully used by the turbine of fig.6 to do work.

§6. Exhaust Purification

Now, exhaust purification is one of fatal issues for modern engines. Zhou Engine has a unique advantage in exhaust purification.

According to the current technology, for a catalytic exhaust purification: The first, the rated working temperature should be higher than 600 °C. The second, there must be enough chemical reaction time inside the catalytic exhaust purifier. The third, … Fig.6 is changed to fig.8. According to fig.8, we can easily implement the first and the second above.

According to the current technology, the rated working temperature of a catalytic exhaust purifier should be higher than 600℃(or 873.15 K). If the working temperature the catalytic exhaust purifier is lower than 500℃, the carbon particles cannot be burned off and need to be filtered out, the NOx catalytic decomposition effect is deteriorated, the urea denitration is required, the HC and CO removal ability is lowered, and the catalytic exhaust purifier is easily clogged.

In a conventional engine, the catalytic exhaust purifier is installed behind the engine and the turbocharger, and before the muffler, the working temperature of the catalytic exhaust purifier is near the final exhaust temperature. If we want to ensure the exhaust purification, we have to maintain a high final exhaust temperature, which reduces the thermal efficiency; if we want to have high thermal efficiency, the final exhaust temperature would be low, the catalytic exhaust purifier would not work good. This is “the dilemma of diesel engines” now. The Atkinson cycle, this dilemma is more serious.

In fig.8:

Point L, is the rated working parameters of the catalytic exhaust purifier of a conventional engine. The conventional engine, point L is also its final exhaust parameter. Its intake parameter is the same as the point A of this turbocharged Zhou Engine. Its final exhaust temperature is T=600°C=873.15K, and its final exhaust pressure is p=0.1013MPa. So, its final exhaust volume within one thermodynamic cycle is V=0.1013*V1/273.15*873.15/0.1013 = 3.1966*V1, its final exhaust volume flow rate F=3.1966*F1.

Point E, it is the rated working parameter of the catalytic exhaust purifier of this turbocharged Zhou Engine. It is also the exhaust parameter of this Zhou Engine, it is before the turbine, it is not the final exhaust parameter of this turbocharged Zhou Engine.

Point D, it is the rated final exhaust parameter of this turbocharged Zhou Engine.

Points D, E, and G are all on the adiabatic expansion curve C-D of fig.5.

Contrast the parameters of point E and point L:

1. The temperature of point E is higher than the temperature of point L, and higher than the lower limit rated working temperature of the catalytic exhaust purifier. That is, when the working condition changes, this turbocharged Zhou Engine engine has a larger margin to maintain the catalytic exhaust purifier regular working, and could avoid expensive urea denitration.

2. The volume flow rates F are much different between point E and point L. If this turbocharged Zhou Engine use a catalytic exhaust purifier that is used by a conventional engine, the chemical reaction time in this turbocharged Zhou Engine will be (3.1966*F1)/(0.3013*F1)=10.609 times of that of the conventional engine, which is too abundant and not necessary. If we set the chemical reaction time of the catalytic exhaust purifier of this turbocharged Zhou Engine equals that of the conventional engine, then the internal volume of the catalytic exhaust purifier of this turbocharged Zhou Engine is (0.3013*F1)/(3.1966*F1)=0.09426 times of that of the conventional engine. Since the internal volume of the catalytic exhaust purifier is filled with the catalyst that rich in precious metals, and its carrier, they are very expensive. Thus, the smaller the internal volume means the less catalyst and the lower the cost, so the cost of the catalytic exhaust purifier of this turbocharged Zhou Engine is far lower than that of the conventional engine. Moreover, the catalytic exhaust purifier of this turbocharged Zhou Engine can work well under a wider range of working conditions. But, the catalytic exhaust purifier of this turbocharged Zhou Engine, its shell is thicker to withstand the gas pressure of 1.5MPa, its internal wall will be coated by insulating ceramics to reduce heat lost, and to avoid its shell too hot.

Therefore, this turbocharged Zhou Engine, its final exhaust temperature (the temperature of point D) does not affect the working temperature of its catalytic exhaust purifier (the temperature of point E), which can well avoid the current “the dilemma of diesel engines”, furthermore, the cost of its catalytic exhaust purifier will be far lower.

In fig.8, there are two stages of adjustable vanes. The stage 1 adjustable vane is adjusted according to the signal of the gas pressure sensor of point M, to eliminate the gas pressure pulsation of point M, to match optimally between the Zhou Engine and the turbine, to achieve higher thermal efficiency. The stage 2 adjustable vane is adjusted according to the signal of the gas pressure sensor of point N, to stabilize the gas pressure of the point N, to stabilize the working condition of this turbocharged Zhou Engine. Because of the stage 2 adjustable vane, this turbocharged Zhou Engine can easily adapt to the high altitude, and can avoid the “turbo lag” of a conventional turbocharged engine. Thus, by cleverly adjusting the stage 1 adjustable vane and the stage 2 adjustable vane, we can achieve M-point pressure without pulsation in a wide power range, the catalytic exhaust purifier works in the optimal temperature range, and this turbocharged Zhou Engine works in the range of high thermal efficiency.

The turbocharger and the turbine in fig.8 can be ordered or purchased on the market according to the parameters we need.

§7. Recycling Exhaust Pressure vs. Utilizing Exhaust Residual Heat

Recycling the exhaust pressure, as this turbocharged Zhou Engine does (seeing Section 5 above), that is, pneumatic energy in the exhaust of this Zhou Engine transforms into the shaft power of the turbine at point J in Figure 6. Which is one mechanical energy transforming into another, the conversion efficiency is much higher than thermal energy transforming into mechanical energy and can reach 80-95%. The recycling device is the turbine, and its power density is very high and higher than a gas turbine. So, recycling the exhaust pressure of this Zhou Engine can be used on the ground, ships, vehicles, and even airplanes.

Whereas we usually utilize the IC engine’s exhaust heat as follows. Use them to generate steam, and then use the steam to drive a steam turbine to generate power. If the steam turbine condenses, the conversion efficiency is about 30%, but the power density is extremely low and can only be used on the ground. If the steam turbine is a non-condensing one, the conversion efficiency is about 15%, lower than the condensing one, and the power density is also very low and can only be used on ships or on the ground.

§8. Advantages

In summary, this turbocharged Zhou Engine has the following advantages —— 1) Using the toothed-rollers, Zhou Engines avoid most of the friction between the cylinder and the piston that conventional piston engines have; that increases the thermal efficiency. 2) By the power-cam and the combustion period, achieving constant-volume combustion increases the thermal efficiency. 3) The co-acting between the turbine and the crafty specific piston-motion-curve, fully recycling the exhaust pressure, increases the thermal efficiency. 4) Compared with a gas turbine, the higher working gas pressure and combustion temperature inside this Zhou engine's cylinders increase the thermal efficiency. 5) By selecting point E and point F, a far smaller cylinder volume is needed than conventional engines, which reduces the volume of this Zhou Engine. 6) Reference “Zhou Engine vs. a conventional four-stroke engine”, a Zhou Engine breaks through two speed limits of a conventional engine, that reduces the volume of this turbocharged Zhou Engine and raises the specific power. 7) Because of the combustion period, even using Heavy Fuel Oil (seeing https://www.dhirubhai.net/pulse/primary-design-example-turbocharged-zhou-engine-vs-wartsila-zhou), the other processes of the thermodynamic cycle (including intake stroke, compression stroke, expansion stroke, and exhaust stroke) can still run as fast as high-speed engines; that dramatically increases the power density. 8) By selecting point E, its catalytic converter is far smaller, has better working conditions, and has a far lower cost.

Moreover, all the technical parameters above, such as pressure, temperature, and compression ratio, are all the typical values of current engines or gas turbines, so we should have no technical barrier in realizing this turbocharged Zhou Engine. This turbocharged Zhou Engine has no pulsation in its total exhaust and will avoid almost all conventional engines' noise. This Zhou Engine sets its pistons in pairs, and the two pistons of each piston pair are precisely reversed motion mutually, which counteracts almost all its vibration.

This turbocharged Zhou Engine would obtain higher thermal efficiency by stage-cooling the compressed intake air.

For more about this invention, please see "About Zhou Engine" .

For more about "turbocharged Zhou Engine" and which prototype design, please see “An Outline Design of Zhou Engine & Its Comparisons”.?

Please see "An example of Zhou Engine working as a combustor of a gas turbine".?

Comparison a Zhou Engine with a conventional engine, please see "Zhou Engine vs a conventional four-stroke engine".

For using of heavy fuel oil, see "A Primary Design Example of Turbocharged Zhou Engine Vs. Wartsila 12V32".?

Please see "A designed example of turbocharged Zhou Engine".??

Welcome anybody to argue about all the above statements.

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