Experimental evaluation of a solar-assisted heat pump system as a hybrid thermal reactor for energy-efficient drying of agricultural biomass

Review on advanced of solar assisted chemical heat pump dryer for agriculture produce

<p>This study evaluated the performances of solar assisted heat pump dryer (SAHPD) and heat pump dryer (HPD) for drying of <em>Curcuma xanthorrhiza Roxb</em>. The HPD and SAHPD reduced mass of <em>Curcuma</em> from 30.70 kg to 7.85 kg needed 10.5 hours and 8 hours with average temperature and relative humidity 49.2oC and 26.5%, and 57.7oC and 19.8%, for SD and SAHPD respectively. The moisture of Curcuma dried from 3.167 db to 0.065 db with an air mass flow rate of 0.121 kg/s. The SAHPD reduced the drying time about 24% compared to HPD. The drying rate and the specific energy consumption were calculated in an average 1.05 kg/h and 1.36kg/h, and 1.17kWh/kg and 2.07kWh/kg for HPD and SAHPD, respectively. The specific moisture extraction rate and the dryer thermal efficiency were calculated in an average 0.931 kg/kWh and 0.521 kg/kWh, and 61.0% and 34.3% for HPD and SAHPD, respectively. Whereas, the pickup efficiency and the coefficient of performance of the heat pump were calculated in an average 57.5% and 59.2%, and 4.03and 4.35 for HPD and SAHPD, respectively. The SAHPD is capable of drying <em>Curcuma</em> quickly because of the high pickup efficiency and high drying rate.</p>

Experimentation on solar-assisted heat pump dryer: Thermodynamic, economic and exergoeconomic assessments

This research investigated the performance of a solar‐assisted heat pump dryer (SAHPD) with heat recovery to reduce the amount of thermal energy needed for drying chili peppers. The dryer selected for the experimental study consisted of a heat pump, a greenhouse cover and multi trays. It was found that the SAHPD with recovery gave better drying performance than a traditional dying method. The dryer system can offer drying time, drying efficiency, coefficient of performance and specific energy consumption of approximately 24 hr, 33.2%, 3.17, and 2.21 kWh/kg, respectively. Furthermore, the SAHPD with heat recovery provided a higher drying performance than without the heat recovery although the ambient condition changed. Base on the economic analysis, the payback period and net present value of the SAHPD with heat recovery were approximately 1.9 years and 915.60 USD. The SAHPD with two drying rooms also yielded better drying performance than the SAHPD with one room.Practical applicationsDrying is the process of moisture reduction to a safe limit of moisture content, which allows agriculture to extend the shelf life of the crops by restraining the growth of microorganism. In chili peppers drying process, a solar assisted heat pump drying as one of hybrid solar dryers is preferred because heat and mass transfer rate are rather high and it offers the ability to operate both daytime and nighttime. However, the exhausted air to the ambient still has considerable thermal energy. Thus, the heat recovery system has been employed to design and fabricate inside the dryer. Findings of this research contribute to the evaluation of heat recovery in a typical solar assisted heat pump dryer in terms of drying efficiency and economic feasibility in order to be a guideline for small and medium‐sized enterprises.

Review of solar assisted heat pump drying systems for agricultural and marine products

Study and optimization of the influence of the water tank temperature on the performance of a solar assisted multi-source heat pump drying system

Comparison of solar dryer and solar-assisted heat pump dryer for cassava

In this paper, we present the research results of the effect of the weather conditions on the performance of the solar assisted heat pump drying system for red chili. This system was designed and installed in Vinh Long University of Technology and Education for drying of red chili to evaluate the effect of the weather conditions of Mekong River Delta of Vietnam on the performance of the solar assisted heat pump drying system for red chili. The results of the experiment showed that the average values of the specific moisture extraction rate (SMER) of the solar assisted heat pump drying system for red chili in three days of the fair day, intermittent cloud sky day and overcast sky day are 0.37 kg/kWh, 0.33 kg/kWh and 0.26 kg/kWh, respectively, and the contribution of the useful heat gain of solar collectors in three cases are 14.5 kWh, 8.91 kWh, and 0 kWh, respectively, while the corresponding amount of energy consumption of this system are 18.2 kWh, 20.4 kWh and 24.3 kWh, respectively.

Experimental performance analysis of novel indirect-expansion solar-infrared assisted heat pump dryer for agricultural products

Analysis on characteristics and operation mode of direct solar collector coupled heat pump drying system

Experimental energy, exergy, economic and exergoeconomic analyses of batch-type solar-assisted heat pump dryer

Performance of evaporator-collector and air collector in solar assisted heat pump dryer

The performance of a solar assisted heat pump dryer integrated with biomass furnace has been designed and evaluated for drying red chillies, and drying kinetics of red chillies were evaluated. The red chillies were dried from 22 kg with moisture content of 4.26 db to moisture content of 0.08 db which needed 11 hours, with the average drying chamber temperature, drying chamber relative humidity, and an air mass flow rate of 70.5°C, 10.1%, and 0.124 kg/s, respectively, while the open sun drying needed 62 hours. Compared to open sun drying, this dryer yielded 82% saving in drying time. The drying rate, the specific moisture extraction rate, and thermal efficiency of the dryer were estimated in average to be about 1.57 kg/h, 0.14 kg/kWh, and 9.03%, respectively. Three mathematical models, the Newton, Henderson-Pabis, and Page models, were fitted to the experimental data on red chillies dried by solar assisted heat pump dryer integrated with biomass furnace and open sun drying. The performance of these models was evaluated by comparing the coefficient of determination (R2), mean bias error (MBE), and root mean-square error (RMSE). The Page model gave the best results for representing drying kinetics of red chillies.

The solar-assisted heat pump drying (SAHPD) system uniquely incorporates solar-heating refrigerant through hot water from solar evacuated tubes, offering distinct advantages. This study analyzed three experimental setups: a heat pump dryer (HPD) without solar assistance, SAHPD configuration 1 (C1-SAHPD) with solar-heated refrigerant at the discharge line, and SAHPD configuration 2 (C2-SAHPD) with solar-heated refrigerant between condensers, both for performance and economic viability. The experiments maintained consistent parameters, including 5.5 kg of Pandan leaf (Pandanus amaryllifolius), an airflow rate of 0.135 kg/s, and a refrigerant operating pressure of 9.65 bar. The SAHPDs operated when the hot water temperature in the storage tank reached between 70°C and 90°C, with a daily average radiation intensity ranging from 0.670 to 1.102 kW/m² for heating the water. The study revealed average coefficients of performance (COP<sub>avg</sub>) of 5.34, 5.43, and 6.53 for HPD, C1-SAHPD, and C2-SAHPD, respectively. The specific moisture extraction rate (SMER) for HPD was 2.64, while C1-SAHPD and C2-SAHPD had SMERs of 1.88 and 2.71 at solar fractions of 0.34 and 0.45, respectively. Notably, C2-SAHPD reduced electricity consumption by 46%. The payback period for drying 11 kg of Pandan leaves per day was 4.56 months for HPD, 4.32 months for C1-SAHPD, and 3.84 months for C2-SAHPD. The study concluded that C2-SAHPD was the most efficient dryer system for Pandan leaves based on its higher efficiency, SMER, and cost recovery. Additionally, the performance optimization presented in this study contributed to developing a novel technique for classifying dryer technologies.

Postharvest losses (PHLs) of biomaterials, such as vegetables and fruits, significantly impact food security and economic stability in developing nations. In Tanzania, PHLs are estimated to range between 30% and 40% for cereal crops and even higher for perishable crops such as fruits and vegetables. Open-sun drying (OSD) is the most extensively employed method because of its affordability and simplicity. However, OSD has several drawbacks, including difficulties in managing drying parameters, long drying times owing to adverse weather, and product contamination. The solar-assisted heat pump dryer (SAHPD) is a technology designed as an alternative solution for drying biomaterials and reducing PHL. A limited number of SAHPDs have been constructed in developing nations. Most of the works have concentrated on the performance analysis of the systems. This neglects the techno-economic assessment, which is important to provide both a quantitative and qualitative understanding of the financial viability of the technology. The present study therefore investigates the techno-economic analysis of a novel SAHPD for drying agricultural products, particularly vegetables and fruits. To determine whether the SAHPD technology is technically and economically viable, tomatoes and carrots were dried and analyzed to determine their thermal and economic performance. The results show that the initial moisture contents of tomatoes (Lycopersicum esculentum) and carrots (Daucus carota) were reduced from 93% and 88% to 10% in 11 and 12 h, respectively. The coefficient of performance (COP), drying time (DT), specific moisture extraction ration (SMER) and thermal efficiency () were found to be 3.4, 2.3 kg/h, 1.33 kg/kWh and 54.0%, respectively. The economic analysis was assessed using the annualized cost, lifecycle savings, and payback period for the dryer's life span of 15 years. The initial investment of the SAHPD was $5221.8 and the annualized cost was $1076.5. The cumulative present worth for 15 years was found to be $23,828.8 and $27,553.1 for tomatoes and carrots, respectively. The payback period for tomatoes was found to be 3 years, whereas for carrots it was 2.6 years. Based on thermal and economic performance assessment results, the developed SAHPD is technically and economically viable to be considered for further investments.