a ground-coupled dynamic wall system for new and existing structures.

by:Chengbai     2020-02-21
Introduction people in the industrialized world are constantly in conflict with nature, and although the weather is changing every hour, every day and season, they do everything they can to maintain constant environmental conditions.
Normally, we isolate our home to provide a static shield that protects the living space from these changes, as long as it is practical and releases energy to heat or cool the living space
So we stay comfortable.
The main source of such complementary energy may be abundant but ultimately irreplaceable fossil fuels at present.
Therefore, our residential comfort is provided in an unsustainable way, and in developing countries that are now able to provide equal comfort, the rapid growth of the population has further exhausted our resources.
A new approach is needed.
This paper presents a method and means by which a typical static insulated building housing is converted into a dynamic housing capable of responding to changes in environmental conditions, make it more effective to isolate living space from extreme temperatures.
As a result, the size and energy consumption of the supplemental heating/cooling system are significantly reduced in order to remain comfortable.
The system improves the efficiency of static walls and uses renewable low
Grade energy provided by the sun and stored on the ground around the building.
In essence, it is a solar management system.
Exergy is a term used to define the maximum useful work that can be performed within the system until it is balanced.
Unlike the energy that \"can neither produce nor destroy\", the fire in the system is consumed as a system to achieve balance.
Exergy can be considered as an energy mass or availability of energy to do useful work.
For example, a system consisting of a bag of ice and a box of pop placed in a fully insulated cooler has both energy and energy, I . E. e.
The ice has the ability to cool the soda tank.
At a certain point, all substances are at a uniform temperature. although the energy of the system has not changed, exergy has been lost and the system cannot do further work, the system temperature will remain the same until exergy is added to the system from the outside (e. g.
, The cooler is opened, and the cold tank is replaced by a warm cold tank. )
A thermodynamic system that contains the building and its direct environment is never a closed system, because whenever a new warm or cold front passes through, the sun rises or falls, and the clouds pass through the top of the head, or seasonal variations the use of fire varies with the temperature of the air relative to the ground and the temperature inside the building.
At a distance below the surface, the ground around the foundation of the House has reached the same temperature as the average annual temperature of the surface.
When the air temperature reaches the average temperature, there is no available fire to work with the heat stored in this underground, but even if this underground temperature may be much lower than the room temperature, in winter, this stored solar energy can be used instead of fossil fuels to re-heat the air to the ground temperature.
Again, it can be used to cool hot air during the summer months.
Similarly, sunlight during the day shines on the roof, which can raise the surface temperature of the roof above the temperature required to provide domestic hot water.
The radiation cooling on a clear night can make the temperature lower than the ambient temperature.
This property can be used to cool down before construction in summer.
The means of natural changes in the use of fire are called Earth\'s solar storage technology (GEST).
The rest of this article will discuss how to partially implement GEST by including modified walls that can be coupled to the ground\'s gap air space, and describe the prototype structure of applying the system.
Over the years, a buffer wall using a double facade to provide a buffer temperature zone for the building has been used in many configurations. Aglassed-
In the porch of the house is a practical application of this technology.
Similarly, storm windows are used to provide a buffer between windows and outdoor wind and cold air.
With the energy crisis at the end of 1970, the idea of a buffer House is to take advantage of the low by coupling the buffer inside the wall to the basement of the structure
The heat entering the basement through the basement walls began to be favored by some people.
The buffered house consists of two frames and insulated envelopes separated by a space in which air can flow freely.
The cycle can be forced or natural.
Usually, large glass windows or greenhouses are built on the south side.
The heat generated during the day cycles between shells, warming the interior.
The key to the system is that at night, the air pre-heated from the basement surface cycles between the walls and the temperature is lower than the room temperature, but higher than the outside temperature.
This effectively reduces the temperature difference on the envelope.
This effectively reduces the temperature difference inside the wall, thus reducing the energy required for the heating system.
Booth presents a complete description of the system and information about the real performance of these structures in the Sun/Earth buffer and super insulation (1983).
Figure 1 shows the low
The Heat obtained by the system is compared with the super insulation wall.
Envelopes can also work in hot weather where air from the basement is circulating through the walls to cool down the house.
Although the envelope house has been shown to work at extreme temperatures, a considerable disadvantage can be seen when the external temperature is close to the ground temperature.
Refer again to Figure 1, if the outdoor temperature is equal to the temperature in the buffer space, there is no difference in the temperature on the outer wall, and the insulation in it does nothing.
Heating system in Figure 1b see a20 [degrees]F (11[degrees]C)
Temperature difference on the wall of R13.
Super insulated wall under the same conditions (Figure 1c)
Place the anR13 R19 barrier on the same temperature difference.
A digital model comparing the buffer Wall and the super insulation wall in Syracuse, New York\'s temperature climate shows that the buffer Wall performs better than part of it in midsummer and midwinter.
However, on an annual basis, the buffered House does not show an advantage over the ultra-insulated house.
There are other drawbacks to the application of these previous versions of the envelope house, of which the biggest drawback may be with the double-
Wall construction.
In addition to the expensive price, the two frame walls are also very thick.
In the fire, the smooth vertical air passage inside the walls is also a concern.
Another big drawback is that double
The envelope system displayed at the booth usually requires a new building (1983).
In order to fully address the current energy crisis, it is necessary to adopt some means to reduce the energy use of more than 100 million existing households in the country through some kind of transformation.
Despite these shortcomings, the theory behind the housing buffer is reasonable.
It can complement the energy needs of residential HVACsystem with a considerable amount of off-the-shelf clean renewable energy at low cost.
A new design is needed with the goal of modifying the system as follows: 1.
The envelope is performed dynamically in order to effectively use the insulation on both sides of the Interior under different weather conditions. 2.
The transformation of the existing structure can be easily completed. 3.
The walls do not take up too much space. 4.
The whole system cost-effective.
The result of this effort is the reason for the proposal --Coupling dynamics (GCD)
Wall System Enhanced by practical geosolar low
Storage and Recovery System.
Early results showed considerable potential for energy conservation.
In the two sections below, we first describe the built GCD wall system and then the integrated gest.
Finally, some preliminary results are given.
Transformation of GCD wall system by power wall (skin)
It is a series of panels made of 1 in. (25. 4 mm), foil-faced (both sides)
Multi-ring urine salt-
The insulation sheath is separated by a series of 1/2 × 2 in from the external sheath of the original frame wall. (13 x50 mm)
Thick wooden strips with intervals of about 16. (406)mm apart.
This creates a winding pipe through which the air can pass (Figure 2a).
The end of the path is connected to the basement through a piping system built in 4. (100 mm)drain pipe.
Pipe installation in-
A pipe fan that can be opened, closed or inserted as a condition guarantee.
On the original prototype structure, the GCD skin was installed in an east-
Facing the wooden wall-Framework structure.
This building is rough.
Cut wood on an uninsulated and unsealed cement block to simulate the old building. The wood-
The frame wall is a typical 2x6 for 24 in. (610 mm)centers.
The gap between the bolts is filled with 5 1/2. (140 mm)paper-
Glass fiber insulation board (R-21)
It covers 1/2. (13 mm)gypsum wall-board.
The exterior of the wall is set up with 7/16 sets. (11 mm)OSB (
Targeted shares).
This is the original wall.
As mentioned above, the improved GCD skin is applied to two panels, about 8 each. (2. 5 m)wide and 10 in. (3 m)
High, marked North and South.
The expected thermal resistance of the original wall and the modified wall is 4 in. and 6 in. (100 and 150 mm)
Table 1 summarizes the walls.
When the fan is closed and the pipe is blocked, these values should be valid under static conditions.
Under dynamic conditions, the original wall and refurbished skin will be treated as two separate walls for analytical purposes.
The air can pass through the walls from top to bottom or from bottom to top.
The preferred direction for cold weather operations is from top to bottom, as the air cools and becomes more dense as the air flows along the sheath, thus providing a natural flow-to-flow force.
The following example illustrates the potential of the GCD wall in the climate of Central New York.
Figure 3 shows the expected operating properties of 16x8 ft (128 f[t. sup. 2], 11. 9 [m. sup. 2])
Transformation of ClearGCD wall panel on wood
As mentioned above, specific conditions for external temperature [T. sub. o]= 0[degrees]F (-17. 8[degrees]C)
The room temperature you want ,[T. sub. y], is 68 [degrees]F (20[degrees]C)(1 in Figure 3). The X-
Scaleis the average temperature of the gap space between the previously existing inner wall and the modified outer skin. The Y-
The electrical energy is equivalent (watts)
System temperature needs to be maintained.
The insulation value of the original wall is [R. sub. i]= 21 f[t. sup. 2]*[degrees]F* hr/Btu. R-
The value of the application sheath ,[R. sub. e]
Including air clearance ,[R. sub. a]
Assume 6. 5 and 2. 8 respectively (2 in Figure 3). Note thatthe R-2.
8 only for static mode for air gap (
No room for ventilation)
Slightly different from R-
Air gap value (
Plus entry and exit)
Listed in Table 1.
This change comes from an effective system R-
Values printed on each sheet of foil-
Surface sheaths, used to reduce the heat loss of the vertical reflection barrier on the sheaths adjacent to the closed air gap.
When the dynamic wall is activated and the air space is opened, R-
The air gap value does not apply.
The influence of air gap insulation value can be seen through two horizontal curves (7)and (8)
Figure 3 labeled [Q. sub. static]@ R =[R. sub. e]+ [R. sub. i]+ [R. sub. a]and [Q. sub. static]@ R = [R. sub. e]+[R. sub. i]. (
The insulation value of the external wall panel is not included here).
Horizontal curve (6 in Figure 3)
Is the heat loss before re-installation, without the benefit of an external insulation or air gap. Curve [R. sub. e](3 in Figure 3)
The relationship between the heat flow through the outer skin and the temperature in the gap space.
This linear curve depends only on the difference in the temperature through the wall ,[DELTA][T. sub. e]= ([T. sub. w]-[T. sub. o])
, And the heat resistance of the external skin ,[R. sub. e].
This is the heat lost by the system; i. e.
, The heat transferred to the outdoor is recyclable. [Q. sub. i](4 in Figure 3)
Is it the flux through the inner wall into the [defined gap Space]Q. sub. i]=[DELTA][T. sub. i]/[R. sub. i]where [DELTA][T. sub. i]= [T. sub. r]-[T. sub. w].
Because the HVAC system is providing heat to make up for this loss, this is considered a loss of heat from the purchase.
With a spaceship (static mode)
The thermal resistance of the two walls is in series, and a single heat flow passes through the two walls, I . E [Q. sub. e]= [Q. sub. i].
The gap space assumes the temperature at which the two curves intersect ,[T. sub. w_static]
, The expected heat loss becomes the corresponding value on Y-
As shown in the figure, the ratio is about 95 W.
If the pipe is sealed so that the air space is not ventilated, the overall R-
The value as mentioned earlier.
The case of wall closure or decoupling is where the minimum total heat loss occurs and therefore represents the most energy-efficient operating conditions.
If the wall is coupled so that the air gap is discharged, but the temperature inside the gap remains the same under static conditions, the heat loss will increase to the level shown in the curve (7 in Figure 3).
In both cases, the thermal insulation of the walls has been greatly improved compared to the original walls due to the renovation.
With Wall coupling, the reduction in the purchase of energy can be further improved by changing [T. sub. w].
The dynamic operation of the wall through the basement coupled with the ground, the heat transfer between the internal and external parts is independent of the outdoor temperature and depends only on [T. sub. w].
The total heat loss of the basement source must be subtracted from the living space or the external heat that [lost]Q. sub. e]-[Q. sub. i].
Violet in Figure 3 (5).
Please note that it intersects [Q. sub. e]at[T. sub. w]= [T. sub. r]
, That is, if the temperature inside the wall is equal to room temperature, there is no temperature difference on the inside wall, so there is no loss of heat purchased.
It intersect thexaxis where [Q. sub. e]= [Q. sub. i]
There is no heat transfer between the wall and the basement;
This is the condition to define the decoupling wall.
Walls work most efficiently in static mode, but dynamic operating walls allow for replacement of purchased energy at a higher speed with cheaper renewable energy (though.
Therefore, despite the decline in energy efficiency, the adverse effects of burning fossil fuels on the environment are also the same.
At the same time, economic efficiency.
In GCD Wall operation, this loss of efficiency can be seen in Table 2.
This is a list of heat losses through the wall section shown in figure 3.
In a static operation, the original wall is used as the base, and the modified wall (
(No ventilation space)
31% improvement is shown.
Operate GCD wall in [T. sub. w]= 48[degrees]
The energy loss through the inner wall was reduced from 121 to only 36 W, a decrease of 71%.
It was impressive but lost 241 W from the ground through the exterior walls.
Then the total energy is reduced-128%.
This is OK if there is enough supply
Grade heat can be obtained from ground sources.
If not, some air can be cycled through the walls, reducing the operating temperature to budget the available ground energy during the heating season.
To simplify the discussion, the cost of crossing the air through the wall is omitted.
In fact, the 241 W power supply from the ground is supplemented by the purchase power required to run ablow to move the air.
The cost of air flow may have a lot to do with the heat loss through the well
Insulated wall panels, especially when the panel area is not large.
Figure 4 is another picture of the energy loss of the same wall segment with outdoor temperature of 0 [and the working temperature of the wall]degrees]F to 24[degrees]F(-18[degrees]C to -4[degrees]C)
Average temperature in Syracuse in January.
In this figure, another line is added to indicate the energy used when air passes through the wall, expressed [P. sub. bl](
Power used by blower).
This energy may come from a different source than the purchased heating energy, and therefore may differ in the values associated with it.
There may also be situations where the air is passively moving, for example, when the sun passes the air through the ventilation wall in a cooling mode.
In any case, it must be considered.
In the case of Syracuse, the rated power of the blower is 17 W.
Energy saving requires the total energy loss of the system ,[Q. sub. e]
, Is the sum provided by the heating system, ground and blower.
Each of these values can be determined from the chart shown in figure 4.
According to the climatic conditions, the actual operating range of the wall can be determined.
Minimum operating temperature means that the total cost of heat purchased Plus Blower and fan consumption is equal to the total cost of loss by decoupling the wall ,[Q. sub. s],or: @ [T. sub. w_ min], [Q. sub. s]= [Q. sub. e]-[Q. sub. g]
For these specific conditions, this point is approximately 45 [as shown in figure 4 [degrees]F (7. 2[degrees]C).
Maximum mean ,[T. sub. w_max]
, In the wall, will be the highest temperature available to the grounding source plus any temperature rise caused by the energy generated by the blower, minus half of the temperature drop when the air passes through the pipe.
In the simplest case, the operating temperature will be the temperature of the basement, because it passively balances with the surrounding earth through the foundation wall and floor, and returns the air to circulate through the dynamic wall.
However, by circulating part of the air through the wall, the operating point may be reduced, thus improving the overall operating efficiency.
It may be desirable to operate at these lower temperatures in order to store heat on the ground available on the winter budget, or to prevent excessive cooling in the basement.
On the contrary, the maximum operating temperature may be increased by the heat extracted from the ground warmer than the heat near the basement wall, and the extra cost of operating a small amount of electricity for circulating pumps and fans on Earthto-
Air heat exchanger.
Another option is to increase the available energy on the ground with the integration of geosolar storage technology (GEST)
Discussed in the next section.
John Hait shows in his book passive annual heat storage: improving the design of the Earth Sanctuary the utility of bottling the sun for a long time
Store heat in the underground for a long time by using a thermal umbrella (1983).
Don Stephens improved Hait\'s design to apply it to super insulated houses that don\'t need to be buried on the hillside (see Figure 5)(2005).
Both systems depend on the Earth as a very large part of the thermal mass surrounding the structure.
During the sunny season, the heat that introduces the ground is drawn by extending the polystyrene carpet around the structure and/or around it.
Polyethylene sheets on foam insulation prevent rainwater from filtering out of the soil and discharge heat from storage.
Both authors built and tested the structure in the northern climate (
Montana and Washington, respectively)
And can keep the temperature at about 18 [degrees]C(64[degrees]F)
No heat is added every year.
A considerable drawback to their system is that the huge thermal mass plus the building housing makes indoor climate control difficult and expensive.
Any change in the thermal state setting of the supplementary HVAC will result in changes in the Earth\'s mass and room temperature.
In addition, neither of these systems can well transform the existing structure.
However, applying an insulated umbrella around a house with GCD walls can cause ong-
Long-term energy storage and higher working wall temperature.
The dynamic heat transfer system between the structural roof, the surrounding ground and the basement has potential benefits over the above passive annualized solar storage.
Transferring heat intercepted from summer radiation to a different temperature position will extend the time spent using solar panels throughout the day.
Also, in winter, it is possible to transfer heat directly from a remote storage location to the basement.
This can be important when heat transfer needs to be accelerated during very cold periods.
The geosolar component of the prototype GEST house is shown in figure 6. The roof-
An integrated solar collector was manufactured by reverse laying
Run the radiant heat system under the steel roof.
The tube at intervals of 6.
Separate, placed in the aluminum heat transfer plate between 5 in. (127mm)
The roof top plate allows the application of 6 in. (152mm)
Asphalt Tile and steel or aluminum roof.
The heat collected here can be transferred directly to the ground through a combination of any one or ten underground coils distributed around and under the structure. A 1500 gal (5700 L)
The water tank under the structure can also be heated and heat is transferred to the underground cells during dark hours.
Keep the heat underground through a layer of expanded polystyrene, extending 16 in. (4. 9 m)
From the walls around the building.
Foam is 4. (100 mm)
The wall is thick and tapering to 2. (50 mm)
On the outer edge.
The polyethylene flakes are combined with the gravel layer to prevent surface water from penetrating into warmedearth and rinse off the heat captured.
From the outside of the finished structure, there is no obvious sign of geo-solar storage, solar collectors or GCD walls.
Results on May 2, 2010, an experiment was conducted on an unusually warm day to test the walls in cooling mode.
The southern part of the wall is monitored through its cross
Section, as described above.
The temperature and relative humidity sensors are placed at the inlet and outlet ports of the gcd Wall segment.
Flow through the wall from the bottom-
By an in-line duct fans.
The measured flow at the inlet is about 200 and 120 cfm (94 and 57 L/s)
, Indicates that there is enough distance between the wall and/or the outside.
The results are shown in Figure 7.
Figure 7a shows starting from the fan throughout the test-up (top trace)
Close the fan completelydown (
Trace through the bottom of the fiberglass)
An hour later (
Second down).
Temperature/RH data recorders are placed in the inlet and outlet pipes.
The temperature is distributed in the middle of the wall.
The energy of the wall to air abandonment is not only a function of temperature change and flow rate, but also a function of any potential heat exchanged between the air and its surrounding environment.
Temperature/RH data for inlet and outlet pipes are plotted on the psymetric chart and analyzed using psymetric analysis (ASHRAE 2012).
The results are shown in Figure 4b.
Heat removed from the wall at the beginning-
Peak at 200 W or about 30 W /[m. sup. 2]over the 7 [m. sup. 2]
In the surface area of the panel, the energy consumption of the pipe fan is 17 W.
Two sets of temperature data collected from wall operation in cold weather conditions (heating mode)
In figure 8 is drawn on the cross section of the wall.
Both sets were taken in January 23, 2011.
One of two Eastern
Part of the wall (labeledNorth)
It is running in static mode, while the other is running dynamically, closing the pipeline to the base.
A in Figure 8 shows that the temperature drop on the inner wall remains the same during dynamic operation, while in B the temperature changes greatly.
A larger temperature gradient is shown in C, as well as the heat loss of the dynamic part of the exterior wall
The excess heat lost here comes directly from the basement and eventually from the ground.
Interestingly, the afternoon data concentration is closer to the power side by the gradient of the fiberglass than the gradient in the early morning, although [difference 6]degrees]F (3. 3 [degrees]C)
Temperature outside.
Throughout the morning, bright sunlight has been shining directly on the wall, and the thermal capacity effect of various building materials has become obvious.
In addition, the effect of the radiation barrier in the air gap may hinder the cooling of the OSB sheath.
Under the conditions here, it may be more economical to operate in a static mode.
Part of the next phase of research on GCD walls will be to simulate thermal mass and radiation thermal effects under different building configurations and climatic conditions, and to create algorithms for optimized automatic Wall operations.
The psychrometric analysis of the data in the heating mode usually shows some potential heat transfer within the wall, resulting in condensation (ASHRAE 2012).
This is expected when the warm air moves in a cold environment and must be considered.
There are several options for humidity control, including the use of closed-
Circulation system through the wall and with heat-
Switch in basement or ground.
Another option is to simply take advantage of the heat exchange to provide condensate drains for moisture from the wall to the outside.
When built, the aluminum foil lining on the side of the cold wall is very inert, moving through the regular airflow of the wall, and there is periodic sunlight on it, which seems to provide enough drying.
After a season of operation, the deconstructing of the exterior walls does not show signs of wet problems, but it should be a problem and another area that needs further investigation.
Conclusion This study shows that the system is manufactured and ready-made materials are available without the need for special skills or equipment.
The overall cost of the GCD transformation will directly affect its practicality.
Table 3 lists the material costs of adding GCD walls for this experiment, as shown in figure 2.
The material cost here does not include the meter temperature, switch fan and damper used to automatically operate the wall.
While automatic operation can greatly save costs and significantly increase cost factors, there is no need to take advantage of the readily available
So far, this prototype has proven the energy of the field.
GEST can actually be applied at the same time
A complete system for meals and professional installations, therefore, should become some form of choice for people with a wide range of income.
As shown in Table 1, regardless of the efficiency of the dynamic Wall, the renovation may allow the owner to purchase wall insulation materials between 30% and 65%, which makes the investment risk quite low.
This work shows that the system can install standard build practices and reveals many answers to the system implementation questions from a build perspective.
This also shows that no part of the system needs to be costly.
This structure can be applied to existing residential structures of various types.
On the west wall of our prototype structure, the second shell is built inside the building, which shows that the system is feasible in a house with an amasonry look.
However, the project did not provide enough information to provide a trustworthy cost/benefit analysis.
The project was completed by private investment.
Labor rates are not listed and any applicable design fees are not listed.
As expected, the study demonstrated the potential of the GCD Wall and demonstrated its constructability.
In order to obtain quantitative cost/benefit information, a series of modifications and monitoring of costs, functions and unexpected behaviors at different locations should be carried out.
If we are to significantly reduce our dependence on fossil fuels in a relatively short period of time, it is critical to address the excessive energy used in buildings for climate control.
Together with the fire management system, the GCD wall may be a means to achieve this goal.
The system can be installed in some form in most existing structures.
It can also be used for heating and cooling.
Finally, it makes use of clean renewable resources without incurring too much expensive or high coststech equipment.
Although the return on investment has not yet been shown to be fast, preliminary tests show its prospects.
Special thanks to Lowell E. Lingo (Sr)
Thanks to Roy Roch for the funding of this project, for his valuable help in building a prototype house and for Dr. Roch
Mark Bomberg gave support and advice throughout the development of the technology.
D. Reference Booth1983.
Sun/Earth buff and super insulation.
Cantebury: Built for energy independence, community builder. Hait, J. 1983.
Passive annual heat storage: improving the design of the Earth Sanctuary.
Montana: Rocky Mountain Research Center. ASHRAE. 2012.
Humidity calculation and analysis, version of the Army.
Ashray in Atlanta
ASHRAE bibliography. 2007.
ANSI/ASHRAE Standard 62. 1-
2007, the indoor air quality is still ventilated.
Atlanta: Ashley. Booth, D. , D. Clayton, and B. Henninge. 1980.
Double-shell solar house.
Community Builders. Brock, L. 2005.
Design Exterior Wall: Building Guide for vertical envelope.
John Willie & Sons.
ColoradoENERGY. 2011. R-
Value table: the insulation value of the selected material.
Dow Building Solutions2012. XENERGY XPS -
From the inventor of foam plasticFTC. 2005.
Federal Trade Commission, 16 CFR Part 460, labeling and advertising of household insulation materials: rules of trade regulations; final rule.
Federal RegisterNYSERDA. 2010.
New York State Energy Profile: 1994-2008.
Patterns and Trends.
New York State Energy Research and Development Bureau, Albany. Prowler, D. , and H. Trechsel. 2008.
Mold and moisture dynamics.
Guide to the entire architectural design. www. wbdg.
Organization/resource/moisture dynamics. php.
Sakulpipatsin page. 2008.
Efficient architectural design.
Delft, Netherlands: TU Delft.
Santamouris, M. , and D. Asimakopoulos. 1996.
Passive cooling of the building.
London, UK: James Limited
Siegenthaler, J. 2004.
Modern circular heating.
New York: Delma. Trechsel, H. 2001.
Moisture analysis and condensation control in building envelopes.
American ASTM International Association. Welch, B. 1982. The Double-Envelope House.
Mother Earth NewsLowell E. Lingo, Jr.
Dr. Roy, Dr. Lowell.
Lingo is a corporate company for DFI.
InMorrisville, New York
Utpal Roy is a professor in the Department of machinery and aviation
Syracuse University College of Space Engineering, New York
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...