Modeling High Temperature Heat Pumps with Thermal Storage for Process Integration in Food and Beverage Processing Facilities

Abstract

Food processing facilities are energy intensive, requiring both electricity as an energy source to power process equipment and refrigeration systems as well as fossil fuels supplied to boilers for process heating. As end-user food companies search for options to reduce their energy intensity and operating carbon footprint, there is a need to identify viable alternative to traditional fossil fuel fired boilers to supply process heating. This project explores various heat pumps systems, both with and without thermal storage, to heat hot water used for sanitation purposes in an example poultry processing harvest facility. As a harvest facility, its heating needs are modest since there are no cooking processes present or higher temperature heating requirements; thereby, establishing heat requirements that would be favorable to electrification using heat pumps to achieve greater efficiency compared to an electric boiler.

A computer model of both single stage and two stage heat pump configurations utilizing anhydrous ammonia as the working fluid was developed to simulate the heating performance of the various heat pump options and to quantify the power required to meet various loads as well as to compare the energy used and subsequent CO2 emissions of these heat pump systems. In addition, the energy and operating CO2 emissions for a gas-fired boiler and electric boilers were quantified for comparative purposes. The operating CO2 emissions utilized emission factors from the US EPA with the electric region being the upper Midwest (MROW).

The findings show all heat pump models simulated had lower CO2 emissions than a natural gas fired boiler in the MROW electrical grid subregion where the food processing plant being modeled was located. Break-even electricity emission factors for each heating option were identified to determine the potential deployment of industrial heat pumping technologies beyond the MROW region. The results from this study support a further technoeconomic analysis to quantify the capital and operating costs associated with the deployment of electrically driven heat pumps as an alternative to natural gas-fired boilers in industrial food and beverage processing facilities.