Why Solar Cooling?
Imagine...being able to fit a solar air conditioning system
to your building that would result in dramatic reductions
in electricity consumption and massive reductions
in green house gas emissions.
powered by the Sun,
yet Modular, Scalable and Easy to Implement!
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HOW DOES SOLAR AIR CONDITIONING WORK?
Solar thermal collectors (as used in domestic hot water systems) use the sun's energy to produce hot water, which is stored in a heat insulated tank. Hot water is circulated in a closed loop to a machine called a 'chiller'. The Chiller absorbs thermal energy from the hot water, and uses this energy to produce cold, using an ammonia absorption refrigeration cycle. Cold water is produced in the chiller and this is circulated in a seperate chilled water closed loop, thus distributing the cold around the building to provide cooling.Since both the hot water and chilled water loops are closed, no water is consumed in the process.
Many successful demonstration systems have been set up around the world, many of them as part of academic research projects. These demonstration sites have proved the effectiveness of solar cooling systems in real world applications. The results have demonstrated high levels of comfort combined with reduced electricity costs and significant environmental benefits. There have however been several significant barriers preventing the widespread commercial adoption of these systems.
WHAT HAS PREVENTED SOLAR AIR CONDITIONING FROM WIDESPREAD ADOPTION?
Existing systems are:
- Prohibitively Expensive
- Complicated to engineer, requiring advanced custom engineering for each installation
- Lack scalability
- Typically require “several Ph.D.'s per kW”
What is needed are systems that are:
- Simple to design and install
- Scalable according to the size of the application
- “Turnkey” operation
WHAT IS OUR DIFFERENCE?
NWM has developed a simple, scalable and inexpensive turn key solution. Each of the key system components have been optimised to facilitate an easy to install, powerful and efficient solar air conditioning system. The NWM system facilitates the widespread adoption of solar air conditioning for a multitude of applications globally.
Water is heated using the sun’s energy.
Solar Air Conditioning Unit
Worlds first packaged solar air conditioner, containing compact SolarFrost IceBook Chillers and heat rejection fans.
Cold is produced where it is needed!
Cold Air Blowers
Takes chilled water from the IceBooks and produces cold air.
Hot water is stored in tanks to facilitate operation of the system when the sun is not shining.
THE SolarFrosT SOLAR AIR CONDITIONING SYSTEM
SOLARFROST ICEBOOK CHILLER
The compact nature of the IceBook allows the chiller to be tightly integrated with the heat rejection fans and the solar collectors. The result… the worlds first Packaged Solar Air Conditioner.
The chiller is the heart of any Solar Cooling system. Chillers take in hot water, and provide chilled water, which is then circulated to air handling devices and radiant cooling devices which cool the building.
Current competing chillers are bulky and expensive. New World Machines partnered with SolarFrost Research in 2010 to form a new joint venture company, SolarFrost Labs. The aim: to successfully commercialise a low cost, scalable chiller specifically designed for Solar Air conditioning and refrigeration applications. The result was the SolarFrost IceBook. IceBook revolutionises the Solar Cooling industry by enabling low cost, reliable and scalable systems to be developed.
How it works
The IceBook is a completely new type of cooling machine. It is revolutionary due to its patented cooling cycle, which allows ammonia absorption cooling under temperature conditions that were impossible until recently. Even more surprising is the construction principle and its shape. Contrary to conventional cooling systems which are made of a number of heat exchangers connected by a rather complicated network of bent tubes and fittings, the IceBook is simply built as a block of sheets of different materials, like a book. Micro-channels exist on each layer, and miniaturised components are created on each layer. The result is an inexpensive, mass producible chiller featuring high efficiency and a dramatic reduction in size.
- massive size reduction
- almost no moving parts
- low maintenance
- high efficiency
- low cost
IceBook Chillers are approximately 97% more compact than conventional chillers. The compact nature of IceBook technology supports a revolutionary new architecture of distributed cooling.
Solar collectors convert the light that penetrates its glass panes into heat, and subsequently into hot water. Given the higher water temperatures required for the NWM system, high quality vacuum tube collectors are the recommended collector type. NWM vacuum tube collectors are highly efficient and generate very high temperature water whilst using a minimal amount of roof space. Stagnation temperature is the maximum temperature achieved by a solar collector and is reached when total heat losses balance the energy absorbed by the collector, in practise this may be considered to occur when there is no flow of liquid through the collector. High stagnation temperature of a solar collector is an indication of excellent thermal insulation of the collector. NWM vacuum tubes have high stagnation temperatures, resulting in superior performance of the cooling system, even under less than ideal sunshine. It also translates into less roof space required for the solar collector field.
Intelligent Control System
An intelligent control system is required to efficiently control the various components of the system, ensuring the desired comfort levels as well as overall energy efficiency and reliability of the system. NWM’s innovative control system defines a new standard in solar cooling controllers. The system consists of a number of sensor and control nodes, all wirelessly connected using the cutting edge Zigbee “mesh network” wireless protocol. A central control unit receives information from all nodes, and is able to implement intelligent control strategies based upon the received information. Pumps, dry coolers, auxiliary backup chillers and valves are all controlled to achieve optimised performance of the system. Remote control and detailed performance monitoring is possible via Internet browser or mobile phone.
Entra has developed optimised heat exchangers specifically optimised for use with IceBook. What this means is that our cold air blowers are able to produce cold air from cold water in a remarkably efficient manner. If cold air at 16 degrees is required, then cold water of 14 degrees centigrade will suffice, several degrees higher than other air blowers require. The result: lower loss of energy, less demand placed on the Chiller, reduced electricity consumption by fan blowers and pumps and enhanced overall system efficiency.
An alternative and very effective way of cooling interior building space is through the use of radiative cooling. Cold water flows through special pipes, typically mounted in the ceiling. Radiative cooling results in a very natural, gradual reduction in temperature without the unpleasant drafts associated with forced air systems. Radiative cooling systems work very well with Solar Cooling systems.
ROOM COOLING DEVICES
Room Cooling Devices use cold water generated by the IceBook to cool interior building spaces. NWM utilises two primary types of room cooling devices, cold air blowers and radiant cooling devices
Cold Air Blowers
IceBook chillers may be used with many off the shelf air handler units, which take in chilled water and produce a chilled air flow. They do this by blowing air over a coil which has cold water circulating through it. Such a device is technically referred to as a water/air heat exchanger. Heat from the air is removed by the fluid flowing through the coil. The problem with existing devices is that they have poor efficiency. As a result, there is a large temperature difference between the circulating liquid and the resulting airflow.
Storage tanks may be used to store hot water, thus allowing the IceBook to be powered even when the sun is not shining. In this way it is possible to size the tank to support 24 hour operation of the air conditioning system where necessary. A wide variety of tanks may be used, either pressurised or non-pressurised, depending upon the application.
NWM systems have an optional dessicant dehumidification unit. This unit dehumidifies the air, thus reducing the load placed on the cooling system. Latent heat is removed from the inside air through removal of moisture in the air. The overall system efficiency is greatly improved through use of the dessicant dehumidification unit.
Heat buildup needs to be efficiently removed in order to allow for efficient operation of the solar cooling system. Specially designed fans which remove heat from the circulating liquids are used to remove this waste heat, these devices are called dry coolers. NWM Dry coolers feature advanced heat exchanger technology from Entra. This allows for dry coolers optimised to work with the IceBook system. Dry coolers are simple to install and have low maintenance requirements.
Other methods may also be used to remove waste heat. Swimming pools, where available, may be used very effectively to absorb waste heat from the system. Buried pipes, called Earth heat exchangers, may also be used with great effect.
The NWM system has an option whereby a high efficiency electric chiller unit may be connected to the system. The system is configured such that if there is insufficient hot water available to power the IceBook, the electric chiller automatically activates to provide continuous cooling under any environmental conditions. The electric chiller used has a very high coefficient of performance, meaning it is very energy efficient and the system operates on an economically sound basis, even when running in backup mode.
A NEW VISION FOR AIR CONDITIONING ARCHITECTURE
Little has changed in the basic underlying technology of air conditioning systems since they were first adopted on a large scale in the early 20th Century. Building air conditioning plant is typically centrally located, and involves large, expensive and complicated equipment, and significant piping and ducting infrastructure to transport heating or cooling energy to the parts of the building where it is required.
There are problems with this approach:
- Expensive and complicated central plant infrastructure and equipment.
- High maintenance costs
- Single point of failure in central plant room can result in total system outage.
- High density of waste heat in central location that needs to be removed
- Energy losses in the transport of energy to the part of the building where it is required.
IceBook technology allows a paradigm shift in the architecture of Air Conditioning systems, made possible by the extreme reduction in size of IceBook chillers compared with existing chillers.
IceBook allows a distributed, scalable solution to building A/C, consisting of small, packaged solar air conditioning machines geographically distributed around the building location, providing cooling right where it is required, eliminating the disadvantages of central plant located A/C. Just as the development of the microchip allowed for the development of the personal computer, revolutionising the way computing power was distributed and eliminating the need for large mainframe computer rooms, so too will NWM’s distributed A/C model, powered by SolarFrost’s IceBook Technology, revolutionise air conditioning systems globally.
IceBook allows a distributed, scalable solution, providing cooling right where it is required
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