Energy Efficiency of Pneumatic Cylinder Control with Different Levels of Compressed Air Pressure and Clamping Cartridge

Round 1

Reviewer 1 Report

This paper is far from a journal paper, perhaps a conference paper.

Authors does not provide sufficient background, there is only 7 references in the state of art;

There is also no scientific soundness, authors failed to provide their innovative contribution when compared to previous work;

The reduction on pressure was already an indicator on reduction of compressed air consumption but at what cost? Did all the experiences took the same time on the return stroke?;

The experiment is short on results;

Authors need to major improve this document before submitting to journal magazines.

Author Response

Response to Reviewer 1 Comments

Point 1: This paper is far from a journal paper, perhaps a conference paper.

Response 1: We changed paper according to your comments and we hope that paper will meet the requirements of the journal. We made many changes in paper and they are clearly highlighted, using the "Track Changes" function in Microsoft Word.

Point 2: Authors does not provide sufficient background, there is only 7 references in the state of art. 


Response 2: We added ten more references and changed the introduction according to those references. Now, paper have 17 references.

Point 3: There is also no scientific soundness, authors failed to provide their innovative contribution when compared to previous work.

Response 3: At the end of introduction (lines from 62 to 78), we explained the novelty of proposed cylinder control. Also, we added a new section 2.2 where the control is explained.

Point 4: The reduction on pressure was already an indicator on reduction of compressed air consumption but at what cost? Did all the experiences took the same time on the return stroke?.

Response 4: We added new experimental results of dependences of velocity of cylinder piston movement on compressed air pressure in the return stroke (lines from 224 to 231). We also enriched the section result discussion with comments about new experimental results (lines from 249 to 255). We added three more figures and one more table. Cost-effectiveness of proposed pneumatic system is discussed in section 4.1.

Point 5: The experiment is short on results.

Response 5: We added new experimental results of dependences of velocity of cylinder piston movement on compressed air pressure in the return stroke (lines from 224 to 231). We also enriched the section result discussion with comments about new experimental results (lines from 249 to 255). We added three more figures and one more table.

Reviewer 2 Report

In the current paper, an investigation of a different control and actuation logic for piston pneumatic compressors is presented and analyzed. While the work may be relevant for future developments in the field, a few improvements are suggested before publication:

1) In the introduction, the authors should briefly explain why the control logic proposed (varying the intake pressure and effective stroke) can boost the system efficiency.

2) Authors use k=1.4, which is the adiabatic coefficient for air. However, heat transfer losses may not be negligible in the real compression work, depending on the compression ratio. Have these losses been taken into account for the calculation of the gas temperature? If not, at least a statement in this regard should be included.

3) The literature source from which coefficients C1 and C2 was taken should be cited.

4) In the introduction, the authors claim that the pressure control can lead to an energy efficiency improvement. Then, the discussion is mostly done based on compressed air consumption, which is important from an economic standpoint but not a direct function of the energy consumption, which will depend on many other aspects (compression ratio, friction, heat transfer, etc). Please clarify and, if needed, rewrite the introduction accordingly.

5) Literature review is a little scarse for a journal publication. I recommend to make an effort to include a few more references in the field.

Other minor corrections:

• Line 115: "upstream and downstream"
• Table 3 heading should be more precise (savings in which sense?)

Author Response

Response to Reviewer 2 Comments

Point 1: In the introduction, the authors should briefly explain why the control logic proposed (varying the intake pressure and effective stroke) can boost the system efficiency 


Response 1: In the introduction, from lines 62 to 78, we added the next text: “All of previous papers dealt with the problem of increasing the energy efficiency of pneumatic systems in various ways. Some of them proposed new booster valves [3,4]. Another reused exhaust air from one pneumatic component to the same [5,8,9,10,15,16], or some other [6,15]. There were papers which proposed new algorithm of control [2], optimization of positioner controller settings [11], and reducing air leakage to improve energy efficiency of the whole pneumatic system [12]. This paper deals with the problem of decreasing compressed air consumption in executive pneumatic systems in a new way. The goal of this paper is to develop the new pneumatic system that uses various levels of compressed air in the working and the return cylinder stroke as well as keeps the cylinder piston rod at rest in final positions by clamping cartridge, during which the supply to the cylinder chambers is cut off. Proposed pneumatic system with various levels of compressed air supply and clamping cartridge enable reducing compressed air consumption and at the same time increasing the energy efficiency of whole pneumatic system. If a lower compressed air pressure is used to supply the cylinder chambers, the compressed air consumption will be reduced. The proposed cylinder control system is presented in chapter 2. In addition to the fact that using lower compressed air in return cylinder stroke enables reducing compressed air consumption, it also leads to decreasing the velocity of cylinder piston movement, that is explained and discussed in chapters 3 and 4. In chapter 4.1, cost-effectiveness of proposed system is discussed.”.

Point 2: Authors use k=1.4, which is the adiabatic coefficient for air. However, heat transfer losses may not be negligible in the real compression work, depending on the compression ratio. Have these losses been taken into account for the calculation of the gas temperature? If not, at least a statement in this regard should be included.

Response 2: In the section 2.1, from lines 148 to 149, we added the next text: “Due to simplicity, the heat transfer losses are not been considered for the calculation of the gas temperature.”.

Point 3: The literature source from which coefficients C1 and C2 was taken should be cited.

Response 3: The literature source is cited in line 157.

Point 4: In the introduction, the authors claim that the pressure control can lead to an energy efficiency improvement. Then, the discussion is mostly done based on compressed air consumption, which is important from an economic standpoint but not a direct function of the energy consumption, which will depend on many other aspects (compression ratio, friction, heat transfer, etc). Please clarify and, if needed, rewrite the introduction accordingly.

Response 4: The paper deals only with the problem of decreasing compressed air consumption in executive pneumatic systems. Other aspects as compression ratio, friction, heat transfer, etc, because of simplicity, we assumed that they are the same in typical pneumatic system as in proposed pneumatic system. Those aspects and their influence will be investigated in future work.

Point 5: Literature review is a little scarse for a journal publication. I recommend to make an effort to include a few more references in the field.

Response 4: We added ten more references and changed an introduction according to those references. Now, paper have 17 references.

Other minor corrections:

Line 115: "upstream and downstream".

Response: The corrections are made.

Table 3: Table 3 heading should be more precise (savings in which sense?).

Response : The heading is changed. The savings in compressed air consumption after second set of measurements.

Author Response File: Author Response.docx

Reviewer 3 Report

The proposed manuscript investigates the energy efficiency of pneumatic cylinder control. The topic addressed is interesting, but there are few improvements recommended:

• The Introduction is too short. The general context has to be described better, the relevance and novelty of the study have to be highlighted.
• The results discussion section should be enriched.

Author Response

Response to Reviewer 3 Comments

Point 1: The Introduction is too short. The general context has to be described better, the relevance and novelty of the study have to be highlighted. 


Response 1: We changed the introduction, and added ten new references. In lines from 62 to 78, we added the next text: “All of previous papers dealt with the problem of increasing the energy efficiency of pneumatic systems in various ways. Some of them proposed new booster valves [3,4]. Another reused exhaust air from one pneumatic component to the same [5,8,9,10,15,16], or some other [6,15]. There were papers which proposed new algorithm of control [2], optimization of positioner controller settings [11], and reducing air leakage to improve energy efficiency of the whole pneumatic system [12]. This paper deals with the problem of decreasing compressed air consumption in executive pneumatic systems in a new way. The goal of this paper is to develop the new pneumatic system that uses various levels of compressed air in the working and the return cylinder stroke as well as keeps the cylinder piston rod at rest in final positions by clamping cartridge, during which the supply to the cylinder chambers is cut off. Proposed pneumatic system with various levels of compressed air supply and clamping cartridge enable reducing compressed air consumption and at the same time increasing the energy efficiency of whole pneumatic system. If a lower compressed air pressure is used to supply the cylinder chambers, the compressed air consumption will be reduced. The proposed cylinder control system is presented in chapter 2. In addition to the fact that using lower compressed air in return cylinder stroke enables reducing compressed air consumption, it also leads to decreasing the velocity of cylinder piston movement, that is explained and discussed in chapters 3 and 4. In chapter 4.1, cost-effectiveness of proposed system is discussed.”.

Point 2: The results discussion section should be enriched.

Response 2: We added new experimental results of dependences of velocity of cylinder piston movement on compressed air pressure in the return stroke (lines from 224 to 231). We also enriched the section result discussion with comments about new experimental results (lines from 249 to 255). We added three more figures and one more table.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors significantly improved the document according to the reviewers suggestions and comments.