Critical Analysis of Process Integration Options for Joule-Cycle and Conventional Heat Pumps

Abstract

To date, research on heat pumps (HP) has mainly focused on vapour compression heat pumps (VCHP), transcritical heat pumps (TCHP), absorption heat pumps, and their heat integration with processes. Few studies have considered the Joule cycle heat pump (JCHP), which raises several questions. What are the characteristics and specifics of these different heat pumps? How are they different when they integrate with the processes? For different processes, which heat pump is more appropriate? To address these questions, the performance and integration of different types of heat pumps with various processes have been studied through Pinch Methodology. The results show that different heat pumps have their own optimal application range. The new JCHP is suitable for processes in which the temperature changes of source and sink are both massive. The VCHP is more suitable for the source and sink temperatures, which are near-constant. The TCHP is more suitable for sources with small temperature changes and sinks with large temperature changes. This study develops an approach that provides guidance for the selection of heat pumps by applying Process Integration to various combinations of heat pump types and processes. It is shown that the correct choice of heat pump type for each application is of utmost importance, as the Coefficient of Performance can be improved by up to an order of magnitude. By recovering and upgrading process waste heat, heat pumps can save 15–78% of the hot utility depending on the specific process.

Heat Pump Bridge Analysis Using the Modified Energy Transfer Diagram

“…Since the presented cost parity curves only depend on the temperature lift ∆T lift , the assumption of constant sink tem-perature T h,out and economic boundary conditions as well as the statistical uncertainty of the COP modelling slightly falsifies the critical temperature lift as target value. The novel targeting method using METD also meets the requirements of Fu and Gundersen [16] and Gai et al [19] for realistic modelling of the temperature change on the process sink side. The conventional approach according to Stampfli et al [11] used a storage-based HRL (cf.…”

“…The Exergy Per total annual Cost criterion (EPC) was proposed by Wang et al [18] to select HPs based on their economic and thermodynamic performance. Gai et al [19] emphasised the importance of matching the correct HP type with the thermal requirement of each process. While, for example, transcritical HPs are better suited for sinks with large temperature changes and sources with small, vapour compression HPs are better suited for near-constant constant sink and source temperatures.…”

Emerging Tools for Energy System Design Increasing Economic and Environmental Sustainability

“…In the last paper on this topic, the authors Gai et al [104] reported on the "Critical Analysis of Process Integration Options for Joule-Cycle and Conventional Heat Pumps". They examined different types of heat pumps and their heat integration into the process.…”

Transient Analysis and Control of a Brayton Heat Pump During Start-Up

“…However, other cycles can be advantageous depending on the temperature profile or the plant where they are used. In their analysis of different industrial heat consumers, Gai et al [8] found that sometimes the transcritical, Brayton or Rankine cycle is optimal depending on the process under consideration. In particular, Brayton-based heat pumps may offer more versatility in design and operability when processes characterized by large temperature glides are considered, as they use single-phase operating fluid and exchange sensible heat with the temperature sink and source [3].…”