University of Phase Change Material PCMs
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 20C to 35C, 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.
Inorganic PCMs are generally Hydrated Salt based materials. Academicians are likely to misguide you into using pure hydrated salts like Sodium Sulphate Decahydrate and so on. Hydrated salts have a number of hydrates and an anhydrous form leading to stratification of material and loss of Latent Heat recovery with time. Hydrated salts also have a sub-cooling tendency. Old generation PCM manufacturers managed to add performance-enhancing agents. These additives do help in delaying the degradation of PCMs for say 100 cycles or thereabout. However, they do not address the basic reasons due to which sub-cooling and degradation happens. Earlier researchers emphasized that it is beneficial to use impure grades of base material as it promotes the nucleation and prevents sub-cooling. However, impurities also promoted nucleation of undesirable hydrates leading to stratification. Experts on crystallography have managed to identify the "Preferred Crystal Nucleation" method. It consists of a "Cold Finger" that nucleates and promotes the growth of desired crystals and "Detoxification" or "Selective Elimination" whereby any impurity that promotes the growth of undesirable crystals is removed. The current methods of PCM manufacturing are like the new generation "Combination Drugs".
We also offer:
Turnkey Advanced Thermal Management Systems (ATMS) for BT Shelters with DG Management Circuitry.
CompaqSelfStak(TM) - Latest Leak-free & Compact PCM Encapsulation for AC-Backup & Telecom.
Retrofit of PCM-based Thermal Dynamics Management Systems in Existing Telecom Shelters.
Battery Jacket for Telecom.
Visit www.pcmenergy.com for a detailed write up on PCMs visit our page Products. It gives general information on all the products like T-series PCM 18-29oC; s-series PCM 25-45oC and U-series PCM 6-33oC. The U-series is strongly recommended for those seeking negligible change in specific gravity when the PCM changes from liquid to solid form and vice-versa. Hot & Cold Packs, Freezer Salts, “Your Choice PCMâ€ÂÂÂ, and Encapsulation are also addressed.
Hermetically Sealed Profile of Any Size Like 16mm*160mm*1000mm OR 20mm*200mm*850mm or …..etc, offered in Polymer or Aluminum filled with desired Grade of PCM i.e. Phase Change Material. We can give PCMs in Aluminum or Pet Bottles, HDPE or SS Balls or in Aluminum Sinks or in any container as per your choice.
We also offer Compact AC Back-up System.
PCM or Phase Change Material widely used in Telecom Enclosures (BT Shelters) is LatestTM29T for Air-condition Back-up AC and LatestTM36S for Free Cooling. We also offer Polymer-based PCM-Filled Profiles Panels and Aluminum PCM-Filled Profiles or any other Container like Balls or Bottles or Heat Sinks and so on. We also supply Telecom Shelters and provide engineering services for Back-up Cooling in Existing and New Shelters. 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. Latest29T is used in India for giving back-up Air-conditioning. 240kg of Latest29T is generally used per BTS. 240kg*175 KJ/kg = 42000 K. Joules of backup. This is equal to 42000/3600 = 11.6 KWH of energy (Theoretical L. H. value of Latest29T is 188J/Kg giving theoretical back-up of 12.5KWH). We can give you False Ceiling "Day-Night" temperature balancer. We can also give Modular Heat Exchanger for "Day-Night" temperature balancing.
Live-Site Trial in a Telecom Shelter after Retro-fitting it with 210 Kg of PCM Latest29T (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 36oC. 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 Minutes After Shut-down | 0 | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 | 270 | 300 | 330 | 360 |
| Average Shelter Temp oC | 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 |
| 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 |
Picture of Live-Site Trial of Shelter is produced at the bottom of the page. Phase Change Material, Advanced Thermal Management Systems (ATMS) for Telecom Shelters with DG Management Circuitry
Turnkey Advanced Thermal Management Systems (ATMS) for Telecom Shelters with DG Management Circuitry.
CompaqSelfStak(TM) - Latest Leak-free & Compact PCM Encapsulation for AC-Backup & Telecom.
Retrofit of PCM-based Thermal Dynamics Management Systems in Existing Telecom Shelters.
Battery Jacket for Telecom.
- Stable Temperature Shipping Boxes for the Pharmaceuticals .
- Green House Heating & Free Cooling.
