Optimum Design and Control of Heat Pumps for Integration into Thermohydraulic Networks

Maximilian Sporleder,Daniel Moog,Thomas Kohne,Matthias Weigold,Max Burkhardt

doi:10.3390/su12229421

Abstract

Germany has become one of the leading players in the transformation of the electricity sector, now having up to 42% of electricity coming from renewable sources. However, the transformation of the heating sector is still in its infancy, and especially the provision of industrial process heating is highly dependent on unsustainable fuels. One of the most promising heating technologies for renewable energies is power-to-heat, especially heat pump technology, as it can use renewable electricity to generate heat efficiently. This research explores the economic and technical boundary conditions regarding the integration of heat pumps into existing industrial thermohydraulic heating and cooling networks. To calculate the optimum design and control of heat pumps, a mixed-integer linear programming model (MILP) is developed. The model seeks the most cost-efficient configuration of heat pumps and stratified thermal storage tanks. Additionally, it optimizes the operation of all energy converters and stratified thermal storage tanks to meet a specified heating and cooling demand over one year. The objective function is modeled after the net present value (NPV) method and considers capital expenditures (costs for heat pumps and stratified thermal storage tanks) and operational expenditures (electricity costs and costs for conventional heating and cooling). The comparison of the results via a simulation model reveals an accuracy of more than 90%.

Highlights

Germany is in the midst of transforming its electricity sector, presently having up to 42% renewable generation
This paper presents a method to calculate the optimal integration of heat pumps into industrial thermohydraulic networks by considering design decisions and operation strategies
The method consists of a heat pump database, a preselection algorithm, a mathematical model, and a simulation model

Summary

Introduction

Germany is in the midst of transforming its electricity sector, presently having up to 42% renewable generation. The decarbonization of the heating sector is lagging behind, especially in industrial process heating—even in low-temperature areas (40–150 ◦C)—with over 90% of unsustainable fuels [1,2]. CO2 pricing and the funding program for energy efficiency and process heating from renewable energies will lead industrial companies to adopt new designs for process heating [3] Regardless of the German government’s decarbonization goals, the integration of heat pumps offers a financial and technical advantage, with potential final energy savings of 6.3% in the German industry [4] To achieve the best efficiency possible, the parallel provision of heating and cooling in thermohydraulic networks with a heat pump should be analyzed in future design processes [5] To achieve the best efficiency possible, the parallel provision of heating and cooling in thermohydraulic networks with a heat pump should be analyzed in future design processes [5] (p. 30)

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