Experimental investigation of a high-temperature heat pump for industrial steam production

Low-temperature flue gas heat recovery acts as an important way for energy saving and emission reduction in industry sectors. It is difficult to reuse low-temperature heat in the industrial production process, upgrading low-temperature heat using a heat pump is a promising approach to pursue. In this work, an experimental prototype of a high-temperature compression-absorption heat pump was conducted and investigated. Driving by low-grade waste heat and a small amount of electricity, using ammonia-water as a working fluid, this heat pump experimental prototype can produce high-temperature (more than 150 °C) process steam for industrial processes. The operation strategies of the experimental system are clarified and programmed into the control system. Two hours of automatic stable operation indicates the operation strategies are suitable for this high-temperature heat pump. The temperature and pressure of the produced steam are 154 °C and 0.53 MPa, respectively. The steam heat output of the heat pump experimental prototype reaches 70.15 kW, in which the electric heating share is 18.9% and the waste heat heating share reaches 81.1%. The experimental results indicate the hybrid heat pump is capable of recovering low-temperature (less than 170 °C) flue gas heat for process steam generation. This work provides a new approach to upgrade low-temperature waste heat for process steam production.