scholarly journals Assessment of a Low Temperature Closed-Cycle Grain Drying System

2019 ◽  
Vol 8 (2) ◽  
pp. 80
Author(s):  
Mingjun Ma ◽  
Kurt A. Rosentrater
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
Drying Methods ◽  
Water Removal ◽  
Closed Cycle ◽  
Pump System ◽  
Heat Pump System ◽  
Grain Drying ◽  
Drying System ◽  
Drying Efficiency

This study analyzed the drying efficiency of a prototype low temperature closed-cycle grain drying system. The main principle of this drying system was the heat pump system working as a dehumidifier. The main component of this drying equipment included a compressor, a condenser, twin evaporators, and a fan. Two drying studies (denoted as trial 1 and trial 2) were conducted to assess the overall drying performance of this low temperature drying system. To calculate the drying efficiency, the total energy consumption was divided by the amount of water removal for each trial; the drying efficiency was reported in the form of Btu/lb of water removal. We also tested corn seed germination to determine if this drying process had an effect on seed germination performance. The drying efficiency results for trial 1 and 2 were 1036 Btu/lb water removal and 869 Btu/lb water removal, respectively; compared to other on-farm drying methods this drying system had fairly high drying efficiency. The germination test results showed that this drying system had no adverse effect on germination performance.

scholarly journals Techno-economic Analysis (TEA) and Life Cycle Assessment (LCA) of a Low Temperature Closed-Cycle Grain Drying System

2019 ◽  
Vol 11 (6) ◽  
pp. 52
Author(s):  
Mingjun Ma ◽  
Kurt A. Rosentrater
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Low Temperature ◽  
Economic Analysis ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Closed Cycle ◽  
Gas Emissions ◽  
Grain Drying ◽  
Drying System

The aim of this study was to understand the environmental and economic impact of the low temperature closed-cycle grain drying system by using techno-economic analysis (TEA) and life cycle assessment (LCA). For TEA, three scales including small (60 bu/batch), medium (600 bu/batch) and large (6000 bu/batch) were chosen for analysis the total annual drying cost and unit drying cost. For LCA, the greenhouse gasses (GHG) emission was the only environmental impact that considered in this study, since the electricity was the only energy source for this drying system. The TEA result shows that the drying costs for one bushel of corn were $0.62, $0.49, $0.46 for the small, medium and large scales of this drying system, respectively, and the drying cost could potentially be lower than grain elevators. The LCA results indicate that greenhouse gas emissions will increase along with the expansion of the drying system since the electricity comes from a local coal-based electricity plant, which potentially makes this drying system’s greenhouse gas emissions higher than other types of drying systems. Farmers can use this method to make decisions when handling their grain.

Determination of Heat Transfer Characteristics of Solar Thermal Collectors as Heat Source for a Residential Heat Pump

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Maarten G. Sourbron ◽  
Nesrin Ozalp
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
Solar Collector ◽  
Heat Transfer Characteristics ◽  
Pump System ◽  
Heat Pump System ◽  
Temperature Heat

With reducing energy demand and required installed mechanical system power of modern residences, alternate heat pump system configurations with a possible increased economic viability emerge. Against this background, this paper presents a numerically examined energy feasibility study of a solar driven heat pump system for a low energy residence in a moderate climate, where a covered flat plate solar collector served as the sole low temperature heat source. A parametric study on the ambient-to-solarfluid heat transfer coefficient was conducted to determine the required solar collector heat transfer characteristics in this system setup. Moreover, solar collector area and storage tank volume were varied to investigate their impact on the system performance. A new performance indicator “availability” was defined to assess the contribution of the solar collector as low temperature energy source of the heat pump. Results showed that the use of a solar collector as low temperature heat source was feasible if its heat transfer rate (UA-value) was 200 W/K or higher. Achieving this value with a realistic solar collector area (A-value) required an increase of the overall ambient-to-solarfluid heat transfer coefficient (U-value) with a factor 6–8 compared to the base case with heat exchange between covered solar collector and ambient.

The Heating Coefficient Experimental Analysis of Solar Water-Assisted Low Temperature Air Source Heat Pump System

2014 ◽  
Vol 953-954 ◽  
pp. 136-143
Author(s):  
Jin Shun Wu ◽  
Yue Bo Hu ◽  
De Zhi Hu ◽  
Hong Wei Liu
Keyword(s):  
Comparative Analysis ◽  
Low Temperature ◽  
Heat Pump ◽  
Compression Ratio ◽  
Hot Water ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Efficiency ◽  
Evaporation Temperature ◽  
Air Source Heat Pump

In winter,Many families use air source heat pump because of the low evaporation temperature of the system, resulting in lower heating efficiency of system. To solve this problem, the low temperature solar assisted hot water was added to the project which is on the basis of air source heat pump, and the system has been tested. After analysis of the collection efficiency of solar collectors at low temperatures and comparative analysis of the temperature cycle, pressure, energy consumption of the low-temperature solar-assisted systems and air source heat pump system, the optimal collector temperature and law of heat pump refrigerant cycle changes of the system were obtained. Theoretically, comparative analysis of low temperature air source heat pumps and solar hot water secondary air source heat pump compression ratio and COP. It gives the key parameters affecting the compression ratio and COP, pointing out ways to improve the heat pump COP. Finally, a key measure to improve the thermal performance of the unit system is proposed, to provide a reference for future practical applications and research. Foreword Air source heat pump in ambient air contains rich low grade solar potential as a source of heat, it has inexhaustible characteristics [1] . The main reason for restricting the use of air source heat pump in northern area of our country is when the outdoor air temperature is low in winter, the outdoor coil frost severe heating efficiency air source heat pump is greatly reduced. Martinez suggested experimental study on the application of solar radiant floor heating systems , solar water temperature is 50-60°C, low efficiency, especially when overcast snow lower system efficiency [2] .In view of the outdoor coil frosting problem, direct expansion solar assisted heat pump water heater system using the proposed by Li Yuwu, from a certain extent alleviated the problem of heat in winter for coil winter fros, improving the heating coefficient and improved the operating characteristics of the unit. However, this system requires the direct absorption of heat in air tube, and the specific heat of air is small, difficult to heat storage, illumination by solar radiation impact, unstable system operation [3]. Based on the above issues, for the low-level office building , the new rural residential , this study presents low temperature solar auxiliary air source heat pump system , the device uses low-temperature solar hot water heat pump system as low , both full use of solar energy , but also eliminates the original system frost problems and improve the efficiency of solar collectors and heat set to improve the evaporation temperature of the evaporator , thereby increasing the compression ratio of the heat pump unit .

scholarly journals Numerical Analysis and Preliminary Experiment of a Solar Assisted Heat Pump Drying System for Chinese Wolfberry

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4306 ◽  
Author(s):  
Zhongting Hu ◽  
Sheng Zhang ◽  
Wenfeng Chu ◽  
Wei He ◽  
Cairui Yu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Electric Energy ◽  
Energy Performance ◽  
Operating Conditions ◽  
Pump System ◽  
Heat Pump System ◽  
Electric Energy Consumption ◽  
Drying System ◽  
Heat Pump Drying

The present work investigated a solar assisted heat pump system for drying Chinese wolfberry. The kinetic characteristic was firstly analyzed through a series of lab experiments. It was concluded that the Page model was the most suitable for predicting the heat and mass transfer of the wolfberry. Based on the wolfberry kinetic model, solar collector model and chamber air model, the coupled drying system model was developed. The accuracy of the mathematic model was determined through comparing with the preliminary experimental results. The influence of operating conditions on the thermal and energy performance of the dryer for the different operating mode was discussed. The drying weight of no more than 75 kg may be preferable in the stand-alone solar drying mode, and less than 15 h was needed to be dried. The electric energy consumption in the solar assisted the heat pump drying mode was lower than that in the stand-alone heat pump mode, and it was recommended that about 50 kg of wolfberry to be dried in the solar assisted heat pump system. Compared to the autumn drying, the reduction in the electric energy consumption was around 9.1 kWh during the 11 h summer drying process. The obtained results demonstrated the feasibility of the combined system for drying wolfberry, and also can provide the basic theoretical and experimental data support for the following research.

scholarly journals Performance and Optimization Study of R290 as Alternative Refrigerant for R22 in Low Temperature Heat Pump System

2021 ◽  
Vol 2108 (1) ◽  
pp. 012089
Author(s):  
Yun Zhang ◽  
Cichong Liu ◽  
Wanyong Li ◽  
Junye Shi ◽  
Jiangping Chen
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Exhaust Temperature ◽  
Discharge Temperature ◽  
Temperature Environment ◽  
Temperature Heat ◽  
Overall Performance ◽  
Temperature And Pressure

Abstract This paper mainly studies the replacement performance of R290 in R22 low temperature heat pump system from the experimental point of view. By comparing the performance differences under different working conditions, it is found that when R22 is directly extracted from the original system and filled with R290, the heat capacity and COP of the system are attenuated, and the compressor discharge temperature and pressure of the R290 system are higher than those of the original R22 system in low temperature environment. Through the analysis of the system components, it can be considered that the main reason for the above phenomenon is that the compressor displacement of the R22 system is too large and does not match the R290 system. Therefore, in order to meet the safety requirements of the system and improve the overall performance of R290 in the low temperature heat pump system at the same time, it is considered to replace the compressor with a smaller displacement which is more matched with R290 in the system. The experimental results show that the compressor displacement optimization of the R290 low temperature heat pump system can effectively reduce the exhaust temperature and pressure of the system and improve the overall performance of the system. The COP of the optimized R290 low temperature heat pump system is 6.5% higher than that of the original R22 system, and the exhaust temperature in the low temperature environment is reduced by 36% to below 80 C.

scholarly journals ANALYSIS OF THE HEAT PUMP OPERATION IN THE LOW-TEMPERATURE RECTIFICATION SYSTEM OF PROPANE-BUTANE MIXTURE

2021 ◽  
pp. 3-8
Author(s):  
Larisa Morozyuk ◽  
Evgeny Kostenko
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Distillation Column ◽  
Flow Diagram ◽  
Thermodynamic Efficiency ◽  
Pump System ◽  
Pump Operation ◽  
Heat Pump System ◽  
Butane Mixture ◽  
Propane Butane

The article presents the results of the analysis of the operation of a heat pump in the system of low-temperature rectification of a propane-butane mixture. High-purity propane is obtained from a propane-butane mixture. A "rectification column-heat pump" system is proposed, which transforms the heat removed during the cooling of the component in the upper part of the column into heat absorbed during heating of the bottoms. In accordance with the energy balance of the system, it has been established that part of the heat pump condensation is not used in the distillation column, but is removed to the environment. The heat pump flow diagram contains one evaporator and two condensers. The operation of the heat pump is evaluated from the standpoint of thermodynamics – by the method of energy analysis of the cycle with R134 and R290 working substances, It has been established that the low thermodynamic efficiency of the heat pump is determined by external irreversible losses in the condensers and the evaporator The advantages of R290 as a working substance of the heat pump have been proved and the required theoretical volumetric capacity of the compressor has been determined.

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