Prospects of using heat pumps for the thermal treatment of concrete in the field

Introduction. In the cold Russian climate, thermal treatment of concrete is kind of a mandatory operation conducted to accelerate concrete curing as part of the manufacturing of reinforced concrete products and structures. In practical work, concreting at low temperatures in the field may be accompanied by a shortage and high cost of energy resources needed to perform such thermal treatment. Materials and methods. A promising economical solution to the problem of thermal treatment of concrete and reinforced concrete products in the field is the use of air heat pump systems. The refrigerant circuits through a compressor, a condenser — heat exchanger, a throttle valve, and an air evaporator. The core element of such a unit is the compressor, which is driven not by an electric motor, as usual, but an internal combustion engine. The heat, generated by the heat pump, is delivered to the reinforced concrete product, subjected to thermal treatment, due to the circulation of the coolant through a supplementary circuit that has a condenser-heat exchanger, flexible connecting hoses and thermoactive formwork, in which fresh concrete is placed. Results. The heat pump, which is the source of low-potential heat energy transfer, represents a separate integrated and universal unit, convenient for transportation and installation on the site. The second element of the unit is the thermoactive formwork, that represents the whole range of devices used to manufacture various reinforced concrete products. The installation of this unit will not take more than 5–10 minutes. An alternative to heat pump systems is an electric thermal treatment unit powered by a gasoline electrical generator. Conclusions. The procedure of manufacturing concrete and reinforced concrete products using thermal treatment by air heat pumps is technically feasible, and its energy efficiency may exceed that of an alternative process, namely, the use of gasoline (diesel) electrical generators.