Optimization of air heating in the Prague main railway station building
Passengers waiting for their trains in the area of the main railway station in Prague have been enjoying fundamentally improved thermal comfort since October this year. It involves air-to-air heat pumps and dozens of air clones preventing drafts and heat or cold leakage.
The air exchange in the public areas of the entrance operating building of Prague’s Main Railway Station, which was completed in 1979 and also in the historic Fant’s building from 1909, was based on natural airflow. The flow was derived from the lowest central entrance from the side of Opletalova Street, side exits to the car park and outdoor service areas and adjoining access to individual platforms in the historic building and below it. The thermal comfort of passengers in the space of both buildings depends so much on the parameters of the outside air, the number of people present and how the entrance door is opened. The exception was not the very unpleasant long-lasting strong draft of cold air in the winter.
Until the time of modernization in 2021, the air intake was partially influenced by air in a combination of hot water and electric clones, the medium construction and efficiency corresponded to the technical possibilities at the time. Electric door air clones were used, without heating the air with insufficient power. The hot water clones were partially non-functional, with low fan power and due to wear. In addition, to achieve a sufficient heating water temperature, also its distribution.
Giant. When viewed from above, the blue arrows show the air inlets to the lower operating building of the station. The red arrows move through the air through the historic building and ascend.
Giant. The original door clones above the entrance from Opletalova Street.
Giant. Side entrance to the parking lot without air clones and after their installation
Giant. One of the original hot water clones near the entrance to the 1st platform
The aim of the modernization was therefore to propose a solution for the replacement of the old non-functional system so that the old equipment could be replaced with a new one without major construction interventions. First of all, it was a need to minimize the problem of “drafts” in the winter months, ie to “close” the building envelope and use a clone to separate the indoor and outdoor environment as much as possible. Another requirement was to install a central control of the operation of all equipment from the control room of the building without personal intervention and, last but not least, to use the systems that will be the least energy-intensive.
The given conditions necessitated the use of systems based on air-to-air heat pumps with heat or cold distribution through refrigerant piping with a relatively small clearance. Furthermore, use air clones designed for demanding operation due to the continuous operation of the station and also install air clones with entrances / exits to buildings that have not been solved in this way.
Giant. The floor plan of the buildings shows the installation of outdoor air-to-air heat pump units and two clones connected to them.
Finding a place for outdoor units on the historic Fanta building proved to be very problematic. With regard to the protection of this architectural monument, the distance of the outdoor units from the two clones is greater than is normally recommended. To give you an idea, the distance between the outdoor unit and the first refrigerant hub to the first air curtain is 135 m. R410A refrigerant is used as the heat transfer medium. The solution was verified by a detailed calculation and design.
Giant. The modernization took place without any restrictions on the operation of the station
A total of 29 air clones were newly installed at 11 inlets / outlets, 29 so-called “AHU kits” for connecting door clones, including controls, and 16 Haier MRV5 outdoor units divided into 11 systems. The total installed heating power is 802 kW at +7 ° C. The installation of all equipment took place without interruption of the station’s operation in the period from March to September 2021.
Giant. New air door clones in the ceiling behind the front door towards Opletalova Street
Giant. The new air clones in the access corridor to the platform (before the modernization on the left and after the modernization on the right) document the fulfillment of the requirement of maximum preservation of the architectural solution of the building.
Giant. Transporting and installing outdoor units on a newer building was not a problem. Their location near the historic building is the result of a compromise with the monument protection authorities and the possible length of the refrigerant piping.