The Effect of Different Filament Arrangements on Thermal and Optical Performances of LED Bulbs

Round 1

Reviewer 1 Report

A fine paper.

Please check trhe following:

In Fig.1 you Name the samples by a, b, c but in the next figures you use 1,2,3. Please harmonize it.

 

Fig 3 and 4 are much to small, Please enlarge them.

Author Response

Reviewer:1

Comments: In Fig.1 you name the samples by a, b, c but in the next figure you use 1, 2, 3. Please harmonize it.

Response: Thank you for your reminder. In this paper, the samples name in Fig.1 was inconsistent with other figures owing to my negligence. Fig.1 has been corrected now.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors investigate several commercial LED light sources regarding their thermal behaviour. There is no detail regarding the supplier or specifications of the devices, such that a proper separation of effects in the measurements is difficult (e.g. efficiency and electrical performance; components are not necessarily identical). It is also not entirely clear what the added scientific value of those measurements is.

However, to some readers the simulation part might be of interest, as well as the measurement idea. I will go into detail in the following section to give an exemplary indication regarding where the article needs improvements.

Data representation: the authors state temperature measurements such as "102.483 [degree Celsius]". That is a very high number of significant digits, and the measurement accuracy of the setup and error treatment is not further mentioned. The closest to an error treatment can be found in Table 2, which mentions an error, but does not go into detail about the origin of said error. Figure size: Figure 3 (b) is the best example of a figure that is compressed beyond readability. Structure: The best example would be Figure 8, which I could not find to be referred to in text. It appears in the section of simulation results, but states measurement orientations in the caption. The reference angle for the bulb orientation is not shown, and it can make a difference, e.g. for the horizontal filament, if the angle is in the plane of vertical and filament axis, or the other orientation. Error analysis and isolation of independent variables: "the efficiency of LED converting input power into heat is 70-80%" How would such a difference effect the measurement? Is the effect of the efficiency stronger than geometrical effects? Language: Several sentences require improvement of the language/grammar: "However, due to there is no effective heat sink installed in the limited space, the heat generated by the chip was difficult..."; "All operation and experiment temperatures were carried out at room temperature of 20 [degC]"; and typos like "mothed" instead of method. Style: This is the least important part. I have not encountered journal publications that use bold font for entire paragraphs, such as in line 52 to 56, before. Choosing a bar plot for Figure 8 hides most of the relevant data, as the first ~90 degree are shared among all data points. Figure 5 suggests a 2D mesh, Figure 7 a 3D mesh. The text does not state the dimensionality.

 

Author Response

Reviewer:2

Comments: The authors investigate several commercial LED light sources regarding their thermal behavior. There is no detail regarding the supplier or specifications of the devices, such that a proper separation of effects in the measurements is difficult (e.g. efficiency and electrical performance; components are not necessarily identical). It is also not entirely clear what the added scientific value of those measurements is.

Response: Thank you for your reminder. All the samples in this paper were from the same batch of products of Zhejiang Emitting Optoelectronic Technology Co., Ltd, which rated voltage of 260V. The temperature was measured by instrument (LED T300B) from LEETS Lighting Shanghai Co., Ltd. The optical performance was measured through integrating sphere from EVERFINE corporation. The presented results may serve as a guide in the heat dissipation design of high-power LED filament bulbs. (Page 2 line 66 to 69 and Page 3 line 81 to 82, 86)

However, to some readers the simulation part might be of interest, as well as the measurement idea. I will go into detail in the following section to give an exemplary indication regarding where the article needs improvements.

Data representation: the authors state temperature measurements such as "102.483 [degree Celsius]". That is a very high number of significant digits, and the measurement accuracy of the setup and error treatment is not further mentioned.

Response: Thank you for your reminder. I wrote an extra 3 at 102.483 degree Celsius due to my mistake and it should be 102.48 degree Celsius. To ensure the accuracy of all number in the paper, all the significant digits are two bits. (Page 4 line 125 to 126, 129, and Table 2)

The closest to an error treatment can be found in Table 2, which mentions an error, but does not go into detail about the origin of said error.

Response: Thank you for your reminder. Third, the maximum error represents the linearity, and the difference between the actual value and the theoretical value is divided by the actual value in this paper. The formula can be written as:

(Page 4 line 127 to 128)

Figure size: Figure 3 (b) is the best example of a figure that is compressed beyond readability.

Response: Thank you for your reminder. Fourth, Fig. 3 and 4 have been adjusted to the optimal state.

Structure: The best example would be Figure 8, which I could not find to be referred to in text. It appears in the section of simulation results, but states measurement orientations in the caption. The reference angle for the bulb orientation is not shown, and it can make a difference, e.g. for the horizontal filament, if the angle is in the plane of vertical and filament axis, or the other orientation.

Response: Thank you for your reminder. I redrew the diagram to show the orientation of the bulb, as shown in Fig. 8.

Error analysis and isolation of independent variables: "the efficiency of LED converting input power into heat is 70-80%" How would such a difference effect the measurement? Is the effect of the efficiency stronger than geometrical effects?

Response: Thank you for your reminder. “the efficiency of LED converting input power into heat is 70-80%”, which is for different types of LEDs. The LED chip used in this paper come from the same type and batch, so the geometric cooling effect is very important.

Language: Several sentences require improvement of the language/grammar: "However, due to there is no effective heat sink installed in the limited space, the heat generated by the chip was difficult..."; "All operation and experiment temperatures were carried out at room temperature of 20 [degC]"; and typos like "mothed" instead of method.

Response: Thank you for your reminder. I have corrected the grammatical errors in the paper. “However, due to there is no effective heat sink installation in the limited space, the heat generated by the chip was difficult to dissipate from inside of the bulb to the environment and seriously affecting the thermal and optical performance of the filament” was changed to “However, due to the lack of effective radiator installed in the limited space, the heat generated by the chip was difficult to dissipation from inside of the bulb to the environment, which seriously affecting the thermal and optical performance of the filament.”, and “All operation and experiment temperatures were carried out at room temperature of 20 ⁰C” was change to “Both experiments were carried out at room temperature of 20 ⁰C”. (Page 1 line 33 to 38 and page 4 line 122)

Style: This is the least important part. I have not encountered journal publications that use bold font for entire paragraphs, such as in line 52 to 56, before.

Response: Thank you for your reminder. I have modified the sentence format in line 52 to 56.

Choosing a bar plot for Figure 8 hides most of the relevant data, as the first ~90 degree are shared among all data points. Figure 5 suggests a 2D mesh, Figure 7 a 3D mesh. The text does not state the dimensionality.

Response: Thank you for your reminder. As mentioned in the fifth, Fig. 8 was changed to a dot-plot. Fig. 5 shows that the multi-block unstructured meshing belongs to 3D and Fig. 7 shows that the temperature distribution of cross section belongs to 2D.

Author Response File: Author Response.docx

Reviewer 3 Report

i need to ask 

why these three shapes? what if the wire be like a zigzag shape.

Author Response

Reviewer:3

Comments: why these three shapes? What if the wire be like a zigzag shape.

Response: Thank you for your reminder. The aim is to get the best way of heat dissipation by comparing these three shapes of LED filament bulb. The LED filament bulb with stretch heights of 5cm has the lowest temperature. Moreover, the shape of the filament can form chimney effect. According to the article “Numerical Analysis and Optimization of thermal performance of LED Filament Light Bulb”, the highest temperature of the zigzag LED filament bulb is about 145 ℃, which higher than 102.48 ℃ of the flexible spiral LED filament bulb. Therefore, spiral LED filament bulb was chosen as the experimental sample.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors improved the article in some of the mentioned points, but the article is still lacking in several aspects, which I will go into further detail in the following bullet points, where I will also comment on the corresponding paragraphs of the response letter.

The manufacturer has been mentioned. This supports the conclusion that the LED filaments are in some sense "identical" as far as this can be ensured. Data representation: The authors reduced the number of significant digits, but did not provide an estimate for the measurement uncertainty. The used device is stated in a vague fashion, and I could not find a manual or spec sheet, such that the accuracy remains unknown to me. It could as well be 0.1 K, making the amount of significant digits as well as the conclusion from the data questionable. Figure size: the authors improved the figure sizes. Structure: Especially regarding Fig. 8, the structure of the article has improved. Figure 8(b) could still mention whether the plot is for simulated or measured data. Language: The fixed sentences contain grammar errors themselves. The language editing is still required. Style: This has been largely improved. However, the whole idea of switching from a bar to a scatter plot in Figure 8, now 8(b), was to avoid the empty space between 0 and 80 degC. The plot still contains largely white space, and the visual accuracy from reading data from the plot is seriously affected.

Overall the atricle has significantly improved, despite most of the changes seeming rushed. An example would be the renaming of section 2 from "Method..." to "Mothod...". When stating used equipment, it is advised to state supplier and component ID, and for the obtained data to include an error treatment. 

Author Response

Reviewer:

Comments: The authors improved the article in some of the mentioned points, but the article is still lacking in several aspects, which I will go into further detail in the following bullet points, where I will also comment on the corresponding paragraphs of the response letter.

The manufacturer has been mentioned. This supports the conclusion that the LED filaments are in some sense "identical" as far as this can be ensured. Data representation: The authors reduced the number of significant digits, but did not provide an estimate for the measurement uncertainty. The used device is stated in a vague fashion, and I could not find a manual or spec sheet, such that the accuracy remains unknown to me. It could as well be 0.1 K, making the amount of significant digits as well as the conclusion from the data questionable.

Response: Thank you for your reminder. The temperature was measured by LED thermal analysis system (LED T300B) from LEETS Lighting Shanghai Co., Ltd. The significant digits of the instrument are two bits. I wrote an extra 3 at 102.483 degree Celsius due to my mistake and it should be 102.48 degree Celsius. As shown in Fig. 1, it is the instruction-basic of the instrument. The LED T300B was calibrated by FAST-CAL, and the significant digits of the accuracy-complete are two bits.

Figure size: the authors improved the figure sizes. Structure: Especially regarding Fig. 8, the structure of the article has improved. Figure 8(b) could still mention whether the plot is for simulated or measured data. Language: The fixed sentences contain grammar errors themselves. The language editing is still required. Style: This has been largely improved. However, the whole idea of switching from a bar to a scatter plot in Figure 8, now 8(b), was to avoid the empty space between 0 and 80 deg C. The plot still contains largely white space, and the visual accuracy from reading data from the plot is seriously affected.

Response: Thank you for your reminder. Fig. 8 shows the simulation data. I also think it make sense to study the temperature distribution from 0 to 90 deg C, so the next step is to study it in detail. However, only the temperature distribution of the vertical and horizontal were studied in this paper.

Overall the article has significantly improved, despite most of the changes seeming rushed. An example would be the renaming of section 2 from "Method..." to "Mothod...". When stating used equipment, it is advised to state supplier and component ID, and for the obtained data to include an error treatment.

Response: Thank you for your reminder. The renaming of section 2 from “Method and Experiment set up” to “Experimental method” in this paper. I will pay attention to these details in future papers.

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

The authors left the document largely unchanged from the latest iteration, such that the accuracy of the measurements is still unknown to the reader that has not seen the response letter. The document itself does not contain an error treatment besides stating a fitting error; how this affect the total resolution is not further explained.

There are are still grammar issues present such as "However, due to the lack of effective radiator installed in the limited space, the heat generated by the chip was difficult to dissipation from inside of the bulb to the environment, which seriously affecting the thermal and optical performance of the filament."

Several figures are still affected from unreadable font sizes, e.g., Fig. 6, questionable axis scaling, e.g., Fig. 8 b, or generally pictures that are too small and of too low resolution, such as Fig. 2.

Author Response

Reviewer:

Comments: The authors left the document largely unchanged from the latest iteration, such that the accuracy of the measurements is still unknown to the reader that has not seen the response letter.

Response: Thank you for your reminder. I revised the article to further clarify the measurement accuracy of the instrument. (Page 3 line 86 to 87)

The document itself does not contain an error treatment besides stating a fitting error; how this affect the total resolution is not further explained.

Response: Thank you for your reminder. The temperature was measured by at least two thermocouples during the operation, so the data is the mean value. It has been explained in the paper. (Page 3 line 90 to 91)

There are still grammar issues present such as "However, due to the lack of effective radiator installed in the limited space, the heat generated by the chip was difficult to dissipation from inside of the bulb to the environment, which seriously affecting the thermal and optical performance of the filament."

Response: Thank you for your reminder. "However, due to the lack of effective radiator installed in the limited space, the heat generated by the chip was difficult to dissipation from inside of the bulb to the environment, which seriously affecting the thermal and optical performance of the filament." was change to “However, there is no effective radiator installed in the limited space, which seriously affects the thermal and optical performance of the filament. The heat generated by the chip is difficult to dissipation from inside of the bulb to the environment.” (Page 1 line 38 to 43)

Several figures are still affected from unreadable font sizes, e.g., Fig. 6, questionable axis scaling, e.g., Fig. 8 b, or generally pictures that are too small and of too low resolution, such as Fig. 2.

Response: Thank you for your reminder. I revised the picture in the article.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.