PCM Energy P. Ltd

  Customized PCMs   

General Products       A.C. Backup        Encapsulation Methods        Doctor Says

We do Retro-fitting of PCM based Air-condition Back-up Systems in existing shelter ..... We give Live-site Trials .....

 

 

PCMs for BT Shelter … Information

Phase Change Material PCM.

 

Phase Change Materials (PCMs) are "latent" thermal storage materials. They use chemical bonds to store and release heat. The thermal energy transfer occurs when a material changes from a solid to a liquid or from a liquid to a solid form. This is called a change in state or "phase." Initially, these solid-liquid PCMs perform like conventional storage materials; their temperature rises as they absorb solar heat. Unlike conventional heat storage materials, when PCMs reach the temperature at which they change phase (their melting point), they absorb large amounts of heat without getting hotter. When the ambient temperature in the space around the PCM material drops, the PCM solidifies, releasing its stored latent heat. PCMs absorb and emit heat while maintaining a nearly constant temperature. Within the human comfort and electronic-equipment tolerance range of 20°C to 35°C, latent thermal storage materials are very effective. The main applications for PCMs are when space restrictions limit larger thermal storage units in direct gain or sunspace passive solar systems. Phase Change Materials may be used in Thermal Enclosures like Telecom Chambers BTS or BT Shelters or solar domestic hot water heating or passive solar space heating/cooling systems.

Glauber's salt, Soda ash, Sodium acetate and Paraffin wax are the most commonly used PCMs in solar heating systems. Although these compounds are fairly inexpensive, the packaging and processing necessary to get acceptable performance from them is complicated and costly. They are not offering a reliable pattern of releasing heat as the chemicals in these PCMs separate and stratify when in their liquid state. These PCMs have not always re-solidified properly. When temperatures dropped, they did not completely solidify, reducing their capacity to store latent heat. These problems have been addressed by packaging phase change materials in thin or shallow containers and by adding clumping agents. Many salt hydrate PCMs have the disadvantage that during extraction of stored heat the material super-cools before freezing. This reduces the utility of the materials and if too severe, it can completely prevent heat recovery. They lose their heat storage property after some cycles. These types of PCMs, however, compare unfavorably with the newer generation of low-cost, highly efficient PCMs. Researchers now label these older compounds as "limited utility" PCMs. Phase Change Materials perform best in containers that—when combined with the PCM—total one inch (25.4 millimeters). However, our T-Series Latest™ PCMs have defied this restriction. The packaging material should conduct heat well; and it should be durable enough to withstand frequent changes in the storage material's volume as phase changes occur. It should also restrict the passage of water through the walls, so the materials will not dry out. Packaging must also resist leakage and corrosion. Aluminum, steel and polyethylene are common packaging materials.

We cannot help making a negative comment on the products offered by other brands. Most of the brands are offering Thermal-Salt 29 that freezes at less than 18^oC, making them practically useless in tropical regions. The shelf life of some of the vendors is hardly 45-60 days, making its use by long distance importers almost impractical. Most of such vendors are not manufacturers of the major ingredients but only compounders. Often, they are one-man-show manufacturers and quote fancy prices for the product and demand a fortune for a sample. With the information technology to their aid, they make fancy web sites and manage to squeeze the buyers. We have six manufacturing units, owned and managed by family members and most of the ingredients are manufactured by us.

Phase Change Materials, PCMs Used in BT Shelter

Latest 29T: Phase Change Material, PCM Latest^TM Brand with Melting Point 29°C and Latent Heat of fusion 175 K.Joule/Kg or 260 K.Joule/liter. It is best suited for Air-Condition Back-up to BT Shelter or Telecom Shelter.

Latest 36S: Phase Change Material, PCM Latest^TM  Brand with Melting Point 36°C and Latent Heat of fusion >230KJ/Kg (260 K.Joule/Kg or 357 K.Joule/liter). It is best suited for Air-Cooled Out Door BTS or Telecom Shelter.

 

Telecom Enclosure:  PCM or Phase Change Material widely used in Telecom Enclosures (BT Shelters) is Latest^TM 29T for Air-condition Back Up AC and 36S for Free Cooling. We also Offer Polymer-based PCM-Filled Profiles or Panel and BatteryJacket, Balls, Pipes, Heat Sinks, Bottles and Aluminum/SS/MS PCM-Filled Profiles etc.. We also supply Telecom Shelter and provide engineering services and offer complete unit, with Air Circulators and Controls for Back-up Cooling in Existing Shelter (Retrofit) and in New Shelters.

 

Back-up Air-conditioning with Latest™29T PCM

Power Failure is very common in developing countries. Most BT Shelters or Telecom Enclosures are equipped with electronic Equipments and Battery for emitting proper signal to the cell-phone users. When the power fails, the temperature inside the BTS start rising very rapidly due to heat generated by the equipments and also due to ambient conditions. Diesel Generators are provided to give back up. However they are largely depended on the alertness of the watchman cum operator at the site. The contractors often delay in sending diesel aggravating the problem. To minimize the dependence on generators, Back-up air-conditioning may be provided by phase change material. Latest™ 29T is used in India for giving back-up to Air-Conditions. 240kg of Latest™29T is generally used per BTS. 240kg*180 J/kg 43200 K Joules of backup.  This is equal to 43200/3600 = 12 KWH of energy ( Theoretical Value is 188KJ/Kg of PCM giving back-up of 12.5 KWH).

Live-Site Trial in a Telecom Shelter after Retro-fitting it with 210 Kg of PCM Latest™29T (10 KWH back-up) 

210 Kg of Latest29T PCM (10KWH) filled profiles were installed in an Existing Telecom Shelter of 2m Length by 2.5m width by 2.7m Height. Five thermometers were installed to measure temperature at various points. The Air-condition was switched off when the temperature was 17.3oC. Ambient temperature was also measured. The battery voltage was observed as per the instruction of the site-officer. The permissible maximum temperature that can be reached was targeted to 36^oC. This temperature was not reached in 6 Hours of the run. In a blank reading with-out Latest29T PCM the target maximum temperature crossed in less than 1 hour.

Important Record.
Time in Hours after Power Shut Down	0		1 Hour		2 Hours		3 Hours		4 Hours		5 Hours		6 Hours
Time in Minutes After Shut-down	0	30	60	90	120	150	180	210	240	270	300	330	360
Average Shelter Temp oC (of 5 Sensors)	17.3	22.4	25.2	27.3	29.1	30.2	31.3	32.1	32.6	32.8	33.1	33.2	33.3
Other Relevant Record
Outside Temp oC	26.5	28	29.5	30	31	31	33	33	32	30	28.5	28	26.7
Battery Voltage	25.18	24.99	24.98	24.74	24.65	24.56	24.45	24.21	24.14	23.89	23.61	23.45	22.94
Shelter Temp Centre Top oC	17.5	23.1	25.8	28.1	29.5	30.6	31	31.7	33	33.5	33.5	34	34.1
Permissible limit of Trial was up to Shelter Temperature of 36oC. The Trial was discontinued as the Battery Voltage went low.
The PCM could have lasted for 1-2 Hours more, if the Battery Voltage had not dropped.

OPERATING EXPENSES COMPARISON USING PHASE CHANGE MATERIAL
	Power available 18 Hours/day. 6 hours load shedding.		Power available 20 Hours/day. 4 hours load shedding.
Expense on	SHELTER WITHOUT PCM	SHELTER WITH PCM	SHELTER WITHOUT PCM	SHELTER WITH PCM
Power Cost	Rs.04,10,625	Rs.05,47,500	Rs.04,56,250	Rs.5,47,500
DG Cost	Rs.09,58,125		Rs.06,38,750	Rs.0,00,000
Total Cost	Rs.13,68,750	Rs.05,47,500	Rs.10,95,000	Rs.5,47,500
Savings over 5 years		Rs.08,21,250		Rs.5,47,500
% Savings in fuel cost.		60%		50%
Only 25-35% of the above savings will be the cost of retrofitting PCM in an existing shelter.
Considerations:
1. Power Cost = Hours of power availability (hrs) X Load (KW) X Cost of Power (Rs. 5/KW-hr) X 365 (Days/year) X 5 years
2. DG Cost = Hours of operation (hrs) X Diesel Cost ( 35 Rs/ltr) X Diesel Consumption (2.5 ltr/hr) X 365 (Days/year) X 5 years
3. Power Cost with PCM is higher as PCM uses energy from AC to charge.
PCM charging cost = Load (KW) X Hours of back-up (hrs) X Days per year X Years X Cost of Power (Rs.5/unit)
4. Intangibles like cost of maintenance of DG set, COP of a/c, "green factor" of no emissions are not taken into consideration.
5. Benefits like 80 % book-depreciation in the first year on capital investments of "Energy Management Systems" is added advantage.
Our company can undertake retro fitment of PCM's on a turnkey basis.

 

TECHNO-COMMERCIAL STATEMENT OF PCM PRODUCT T-series Latest™

Latest™ 25T, Latest™ 20T, Latest™ 18T salts are similar to Latest™ 29T

Phase Change Materials perform best in containers that have a depth of one inch (25.4 millimeters). However, our T-Series Latest™ PCMs have defied this restriction. T-series is the Latest in Phase Change Material, PCM technology, Generation-X. It is not degradable with time. It can be used in thicker layers greater than 1” (> 25mm). This product has made the earlier PCMs obsolete.

 

Table of Cycle No. V/s Latent Heat & Sub Cooling for PCM Latest™29T

Cycle No	100	200	300	400	500	1000	1500	2000	1500	2000	2500	3000
Latent Heat KJ/Kg	196	188	188	192	185	178	175	170	172	175	178	170
Sub Cooling oC	0.5	1.0	0.9	0.8	0.7	1.0	1.1	1.2	1.3	1.2	1.3	1.4

There can be an error of <5% in measurement of Latent Heat and 0.5^oC error in Temperature Sensor.

Thermal Salt Latest™29T

Our Thermal Salt Latest™29T is a mixture of several ingredients. Most of these items are manufactured by us or by our sister concerns. Its properties are as under:

 

Specific Gravity                        :           1.5

Freezing Point                           :           28^oC

Melting Point                            :           29^oC

Latent Heat of Fusion               :           >175 K.Joule/Kg (40 K. Cal/Kg). 255 K.J/ltr (60000 K.Cal/Cu.m)

*Most manufacturers report the heat of fusion in a temperature range, like 20^oC to 35^oC. The specific heat of PCM in this range will get added to the values. For this temperature range

*Latent Heat of Fusion             :           210 K.Joule/Kg (50 K. Cal/Kg).

Shelf Life                                  :           Infinite

Max. Operating Temp.             :           100^oC

The Battery Jacket for Outdoor Telecom Shelter  helps keep the battery at the desired temperature even when the internal temperature of the shelter varies widely.  It thus enables establishment of two-climate zones in the shelter, enhancing the life of the battery.

 

       

 Battery Jacket for Outdoor Telecom Shelter

 

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For Advanced Users: Most PCM users are at the elementary stage of using the PCMs. They are ordinarily not conditioned to talk of any deviations from the systems, they have heard of. Using PCM-29 itself is more than adequate mental kick for them. Some vendors manage to convince them that the use of PCMs will save energy charges for them. The primary purpose of the PCMs is to provide a back-up to ACs and avoid the use of Diesel Generator. The site managers and the watch-man cum operator of the site, may not be sufficiently professional. They often fail to keep the diesel at site and restore to "Keep the Door Open for Cooling" ways to cut corners. The relevance of PCMs is more, if the power failure is  a norm in the area of usage. We have a Brain-Wave. Instead of giving 4-6 hours of Back-up, why not give 12-18 hours of Back-up and eliminate the Diesel Generator???!!! This will, of course needs higher battery capacity. In those places, where the whether and equipments permits, you can eliminate the Air Conditioner by using Day-Night temperature balancing with PCM.

Free Cooling for BT Shelters (Telecom Shelter)

Weather Information

Month	Ahmedabad		Bhopal		Hyderabad		Jaipur		Lucknow		Nagpur		New Delhi
	Mean Temp.oC		Mean Temp.oC		Mean Temp.oC		Mean Temp.oC		Mean Temp.oC		Mean Temp.oC		Mean Temp.oC
	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Max
Jan	11.7	28.4	10.2	25.3	14.7	28.6	7.8	22.5	6.9	22.6	12.4	28.6	7.3	21.1
Feb	13.8	31.3	12.4	28.6	17.0	31.8	10.7	25.7	9.3	26.0