Heat recovery plant: ways to improve energy efficiency

Abstract

One of the ways to reduce the cost of heating production facilities in animal husbandry is the use of regenerative heat recovery plants. However, the existing designs of heat exchangers have a number of design flaws affecting their functionality, in particular, the uneven distribution of the air flow over the surface of a heat exchanger. This, in turn, does not provide for a more complete utilization of exhaust air heat. Using the example of a recuperative heat recovery unit UT‑3000, the authors consider the possibility of retrofitting it with an aerodynamic grid to evenly distribute the exhaust air flow over the heat exchanger surface and reduce energy costs for its operation. To do this, they analyzed the applicability of the aerodynamic grid. The size of a blade chord was taken into account as an optimisation parameter. The pressure losses calculated on the “fan – pallet – heat exchanger” section showed that the use of an aerodynamic grid with a “normal” number of blades would create a minimum airflow pressure loss of 0.73 Pa minimum airflow pressure loss of 0.73 Pa, which is 58% less than in the version without an aerodynamic grid. Further experimental study of the uniform airflow distribution over the heat exchanger surface aimed at improving the energy efficiency of the heat recovery unit requires a new design of a heat exchanger with an aerodynamic grid, taking into account the recommended range of “normal” number of blades from 16 to 21, the blade circumference arc of 95° and the blade pitch angle ranging between 68 and 82°.