Integrated high temperature heat pumps and thermal storage tanks for combined heating and cooling in the industry (original) (raw)
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Application of solar thermal heating and cooling energy to dairy processes: a case study
Zenodo (CERN European Organization for Nuclear Research), 2023
The dairy industry is one of the growing sectors in the food industry with significant thermal energy demand for their processes and temperature requirement of maximum 200 ℃. The use of solar energy for those process will reduce the fossil fuel dependency, greenhouse gas emission, environmental pollution and help to meet emission targets. Therefore, this study investigates the thermal requirements of a dairy company and provides a schematic of two integration concepts between the solar thermal energy system and their processes which are through the common energy supply line and inlets of individual processes. The study involves a case study that uses natural gas-powered boilers, and electrical powered chiller, ice banks and refrigerators to meet heating and cooling energy demand for the processes such as pasteurisation, fermentation and cold milk tanks. The overall energy consumption of the dairy processes is 1315 kWh at the full capacity operation, of which 1195 kWh can be theoretically replaced by the solar thermal energy. The temperature requirements of the processes are between 0 ℃ and 4 ℃ for cooling, and 170 ℃ for the heating. These thermal requirements can be met by using either parabolic trough or linear Fresnel solar thermal collectors along with thermal energy storage. The solar thermal energy integration concepts developed at supply level and process level use steam drum and absorption chiller to transfer the solar energy to the processes. The supply level integration has more advantages due to its easier control over the conventional and solar energy systems.
Journal of Dairy Science, 2019
Anaerobic digestion coupled with combined heat and power production on dairy farms is environmentally advantageous; however, high capital and operating costs have limited its adoption, especially in the United States, where renewable electricity and heat production are under-incentivized. Biogas is also at a disadvantage because it has to compete with very low natural gas prices. The objective of this study was to evaluate the feasibility of integrating absorption refrigeration technology for combined cooling, heat, and power (CCHP) on the farm to help bridge this economic hurdle. A combined environmental life cycle and techno-economic assessment was used to compare 2 cooling pathways with and without co-digestion. We considered using CCHP to (1) displace electricity-driven refrigeration processes (e.g., milk chilling/refrigeration, biogas inlet cooling) or (2) mitigate heat stress in dairy cattle via conductive cow cooling. All cooling scenarios reduced environmental emissions compared with combined heat and power only, with an appreciable reduction in land use impacts when employing conductive cow cooling. However, none of the cooling scenarios achieved economically viability. When using cooling power to displace electricity-driven refrigeration processes, economic viability was constrained by low electricity prices and a lack of incentives in the United States. When used for conductive cow cooling, economic viability was constrained by (1) low waste heat-to-cooling conversion efficiency; (2) limited conductive cow cooling effectiveness (i.e., heat-stress mitigation); and (3) low heat stress frequency and limited severity. However, we predict that with minor improvements in conductive cow cooling effectiveness and in hotter climates, CCHP for conductive cow cooling would be economically viable even in current US energy markets.
Hybrid heat pump for waste heat recovery in norwegian food industry
2013
Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kuhn – Berlin: Universitatsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458\]
2020
This study provides suggestions to decrease hot utility use and impact on the environment of a skim milk powder (SMP) processing plant. These suggestions are based on the integration of waste streams with processes in the production of SMP. To identify appropriate waste and process streams, process integration has proven to be a successful method. This concept addresses the issue of waste heat of a process by pointing out to the importance of the relation between unit-processes. In this study, the integration of waste streams is accomplished by heat exchangers, heat pumps and a zeolite wheel. The general assumption underlying this research, is that recovering heat from unused waste streams decreases hot utility use. Multiple methodologies were used in this study. To accomplish process integration, the pinch analysis forms an essential tool. This analysis was used to identify potential heat recovery schemes in the SMP plant. Furthermore, to fully understand these schemes, a thermal, environmental and economical analysis was done. These analyses were based on mass and energy balances, (in)direct CO 2 emissions and investment and operational costs. Several conclusion can be drawn from the pinch analysis. First, the pinch temperature is 50 • C. This represents the dividing line between processes which require heating and cooling. Second, the heating and cooling demand is known. The SMP production process requires 6.8 MW of external heating and 1.7 MW of external cooling. Third, the amount of recoverable heat is equal to 5.3 MW. Fourth, appropriate heat sink and sources are identified. The heat sources, i.e. waste streams, are the spray dryer exhaust and the the condensate streams from two evaporators. The supply temperatures of the exhaust and the condensate streams are respectively 77, 65 and 55 • C. The appropriate heat sinks are the spray dryer air inlet and the evaporator product inlet streams. The target temperature of the spray dryer inlet and evaporator inlet streams are respectively 190, 75 and 70 • C. Seven heat recovery setups are proposed. In terms of saved energy, the spray dryer exhaust has the most potential for heat recovery. The zeolite wheel is the best performing heat recovery technology in the spray dryer process, with a recovery of 3.5 MW. Furthermore, a heat exchanger-heat pump combination and a stand-alone heat exchanger recover respectively 1.8 and 1.6 MW. In contrast, the evaporation process has less potential for heat recovery. The best performing configuration is a heat pump, recovering 1.4 MW from the evaporator condensate. The environmental performance is strongly related with the amount of energy saved. This is because the most decisive parameter in the environmental analysis is the carbon intensity of natural gas and electricity. The best performing configurations in terms of saved CO 2 emissions are the zeolite wheel (3806 ton/yr), the heat exchanger-heat pump combination (1934 ton/yr) and the stand-alone heat exchanger (1593 ton/yr) in the spray dryer process. In the evaporation section, the heat pump saves 1485 ton CO 2 per year. The total annual costs are derived from the equivalent annual costs of the asset, carbon savings and utility savings/costs. The best performing configuration is the heat pump in the evaporation process. This technology has an annual return of 145 ke per year. Other configurations with a high return are the stand-alone heat exv changer (143 ke/yr), the heat exchanger-heat pump combination (128 ke/yr) and the zeolite wheel (123 ke/yr). The following recommendations can be listed: • To save the most energy and CO 2 emissions in the spray dryer process, the zeolite wheel proves to be the best technology. Annually, the wheel saves 3.5 MW and 3806 ton CO 2. • To achieve the highest economic returns in the spray dryer process, the standalone heat exchanger is the best technology. Annually, the heat exchanger potentially saves 143 ke/year. • In the evaporation section, the heat pump is the best performing configurations, with annual savings of 1.4 MW, 1485 ton CO 2 and 145 ke returns. Some of the limitations of this study are listed below: • The model is based on ideal conditions. This means that the projected results may difer from actual effects of technologies. • The effects of the zeolite wheel and the heat pump in the evaporation section are based on the fact that heat surplus is used. However, the results do not take into account the investment costs and CO 2 emissions associated with a potential heat exchanger to recover this heat surplus. Lastly, my sincere appreciation for my family and friends for their support throughout my seemingly endless time at the university.
ENERGY EFFICIENT AND COST SAVING PRACTICES IN DAIRY INDUSTRIES: A REVIEW
The dairy industry handles a large amount of perishable liquid milk, which has to be processed or converted into value added products. This process consumes a great amount of fuel and electricity per year accounting to a higher production cost. There is a greater concern to minimize the use of energy to save cost and forward hands to conserve natural resources and control the global warming. There are a variety of opportunities available to reduce energy consumption and greenhouse gas emissions in a cost-effective manner. This paper discusses about various energy efficiency practices and energy-efficient technologies that can be implemented at the component, process, facility, and organizational levels to reduce the costs and to increase predictable earnings.
A Quantitative Examination of the Efficiency of a Biogas-Based Cooling System in Rural Regions
This study investigates the efficiency of a biogas-powered cooling system through the utilization of energy and exergy calculations. Biogas, which can be generated and stored in small-scale plants as needed, serves as a viable fuel source for absorption cooling systems. The present research focuses on the biogas consumption of a triple-effect absorption cooling system, specifically designed to supply a fixed cooling load of 100 kW under varying operational conditions. The study highlights the COP (Coefficient of Performance) and ECOP (Exergetic Coefficient of Performance) values of the system, along with the exergy destruction rates of its individual components, at the optimal temperatures of operation. Furthermore, to determine the necessary biogas consumption, the study explores the establishment of dedicated farms for various animal species, ensuring an adequate number of animals for biogas production. The findings reveal a COP of 1.78 and an ECOP of 35.4% at the optimized operat...
Investigations of waste heat recovery from bulk milk cooler
Case Studies in Thermal Engineering, 2014
Waste heat recovery Shell and coil heat exchanger Effectiveness COP Overall energy efficiency ratio Energy savings a b s t r a c t Bulk milk coolers are used to chill the milk from its harvest temperature of 35-4 1C to arrest the bacterial growth and maintain the quality of harvested milk. Milk chilling practices are energy intensive with low coefficient of performance (COP) of about 3.0. Increased energy cost concern encouraged an investigation of heat recovery from bulk milk cooler as one conservation alternative for reducing water heating cost in dairy industry. Heat dissipated to atmosphere through condenser is recovered to improve the energy efficiency of plant. The waste heat is utilized to heat the water which is used to clean the milk processing equipments thus saving thermal or electrical energy used to heat the water separately. Shell and coil type heat exchanger is designed and used to recover the waste heat during condensation process. Heat rejected in condensation process consists of superheat and latent heat of the refrigerant. In this work, attempt has been made to recover complete superheat along with part of latent heat which is a present research issue. The results show that complete superheat and 35% of latent heat is recovered. Heat recovery rate is measured for various mass flow rates. Water is flowing on shell side and refrigerant through tubes. The effectiveness of the heat exchanger is determined and the results achieved are presented in this paper. Significant improvements have been achieved and COP of the system is increased from 3 to 4.8.
The Role of Heat Pump Technologies in the Design of Future Sustainable Energy Systems
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