The CKD CHLAZENÍ, s.r.o. company is responding to the current trend in cooling as well as in developments in the field of permanent winter stadiums.
Concept
The technology for cooling ice surfaces can be divided into cooling by the direct evaporation of the coolant on the surface or indirect cooling by the cooling of heat-transfer fluid, usually glycol, in the plate heat exchanger.
Direct evaporation of the coolant (usually ammonia) on the surface usually presents greater demands and higher costs for the cooling register, but works with a higher level of efficiency that brings about savings of operational costs. The cooling register operates at higher pressures and needs to be welded from steel tubes. The content of ammonia is greater than 1500 kg.
Indirect cooling does not carry the high purchase cost of the cooling register, the distribution of the glycol is through plastic tubes, and its serviceable life is at least 50 years. The increased operating costs are balanced by the lesser coolant charge (cca. 320 kg) in the primary circuit and thereby also greater safety.
Coolants
The most widely used coolant for cooling winter stadiums is ammonia. The primary advantages of ammonia are its low cost, powerful cooling capacity, low energy consumption and its categorisation amongst the environmentally friendly coolants. If all the operational safety rules and principles are complied with its danger to humans and living organisms is reduced to a minimum.
In justifiable cases and in accordance with the legislation chlorofluorocarbons can also be used as a coolant for winter stadiums. From the environmental perspective the R134a or the R404 variants are recommended. The minimal risk of them having a direct effect on humans and living organisms is proportionate to their high cost. From a global perspective, i.e. the impact on the atmosphere's ozone layer, CFCs are dangerous mainly for future generations.
Compressors
The basic equipment of the machinery units is a coolant compressor. Up till now reciprocating compressors in a solo version have been dominant, together with one standby compressor. Simple regulation, the possibility of using waste heat (the temperature of superheated steam reaches 110°C), the favourable course of the cooling factor and the low purchase cost put this approach in first position. Combined units offer an easy method to control, and a secure backup, though at a higher cost.
Screw compressors are used particularly in halls with minimal regulatory requirements. The effect of the cooling factor in the regulation of the power is significantly negative. Neither is the use of waste heat as effective; the temperature of superheated vapour is about 70°C. The combined unit with screw compressors provides control by the start up of individual machines; during the regulation of the compressors an adverse effect of the cooling factor is manifested and the utilisation of the waste heat is low.
Turnkey Supply
Long-term experience in the design and operation of winter stadiums enables the company to achieve high technical and economic parameters in the course of their operation. The results include modern winter stadiums and machinery units with automated operation requiring only occasional supervision, a reduction of the coolant charge, the use of waste heat for the production of hot service water, water for ice resurfacers and snow pits, an increase of the serviceable life of the cooling circuit and high operational safety.
The CKD CHLAZENÍ, s.r.o. Company is able to provide all the requisite activities related to construction or reconstruction:
- The preparation of the project documentation for the building proceedings and their implementation
- The manufacture of individual appliances
- The construction and installation of the technologies, including electro-installation and instrumentation and control
- The commissioning and the turnkey supply of the completed work to the customer
- Servicing
Construction of new stadiums, including roofing
In cooperation with construction companies CKD CHLAZENÍ, s.r.o. provides everything, from the preparation of the project documentation and the building permit to the handover of the turnkey supply to the customer, including a guarantee for the technological equipment. Machinery, pressure equipment and the measurement, control and regulatory devices are provided by the company itself. Also included is the service equipment and its availability within 24 hours.
The Reconstruction and modernisation of stadiums
This ensures superior technical equipment and economic results in terms of an overall annual evaluation. The reconstruction that CKD CHLAZENÍ, s.r.o. provides involves either the entire cooling circuit or just the cooling surfaces and/or the machinery units. The reconstruction of the cooling surface includes construction work, insulation, new equipment, surrounds and the supply of a new cooling register, both for the direct evaporation of the coolant and for the distribution of a cooling medium, usually glycol. According to the customer's requirements and the scope of the reconstruction it is also possible to include the distribution ducts as a part of the work.
Reconstruction of the machinery units that is based on the modernisation of the condensation side of the cooling circuit consists of equipping them with evaporative condensers with a water treatment unit. Replacement of the tubular heat exchangers provides savings of energy costs; the content of coolant required is significantly lower. This also applies to the evaporator side in the case of indirect cooling of the surface and the replacement of the tubular evaporator by a plate model in an assemblage with the coolant collector.
Modernisation of the machinery unit, involving the compressors, includes equipping them with the MODI-PRO control system, which is able to control the operating mode of the cooling circuit and can also communicate with a superior system. When it is equipped with a modem it is possible to monitor the mode of operation and also discover any faults from the detached workplace.
The aim of any reconstruction is a higher technical level, the improvement of their working environment for the operators and an increase in operational safety, which CKD CHLAZENÍ, s.r.o. continuously endeavours to achieve.