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 applications Drying 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.

Cold storage is one of the most widely used and effective processes to preserve shelf-life harvested agricultural products during long periods. Research to date has not yet determined the energy management of pre-cooling methods of green cabbage. This study seeks to investigate the cooling performance of the cold storage, keeping green cabbages with good quality and to report different pre-cooling strategies. The cold storage specifications included 15 HP compressor with a voltage of 380 V, a temperature range of -50 to 50°C, and R22 refrigerant. The mass of green cabbage was examined with three values of 30, 40, and 50 kg. Moreover, the pre-cooling strategies of the green cabbages were divided into four scenarios including the parallel pattern in the front zone, staggered pattern in the front zone, parallel pattern in the back zone, and staggered pattern in the back zone. The experimental results revealed that the coefficient of performance (henceforth COP) was significantly affected by the mass of the cabbage and cooling zone of the cold storage. While the pattern in case of 30 kg cabbage precooling had a slight effect on cooling performance due to the lower density arrangement and heat extraction. The highest COP appeared at the 30 kg cabbage precooling with the strategy of staggered pattern in the front zone. The COP value was 2.61.

Falling on the floor has been one of the most common causes of breaking a bone. Falls in senior homes and care facilities can lead to immobility symptoms and treatments. Rubber flooring is a great alternative for fall protection. Thus, this study aimed to investigate the effects of organic blowing agents (dinitroso pentamethylene tetramine and azodicarbonamide) on the physical and mechanical properties of natural rubber foam used for laminated floor tiles. The curing temperatures were also examined in the range of 140–160 oC. From the experimental results, the blowing agent was an important component added to the rubber foam layer at various contents and temperatures. The compression set increased when curing temperatures and adding blowing agent increased. With an increase in the curing temperature, the elongation at break decreased. The findings indicated that the mechanical properties of natural rubber foam were significantly affected by the kind of blowing agent and the curing temperature. Finally, an optimal energy absorption was found in the dinitroso pentamethylene tetramine condition with 3 phr and the curing temperature of 160°C, which offers the maximum energy absorption value of 110 J.

Over the years, plastic water bottle manufacturing, especially PET (Polyethylene terephthalate) bottle has been steadily increasing due to its toughness, transparency, and chemical properties. However, most manufacturers have to spare time, and cost, verifying their prototypes in accordance to the Thai Industrial Standard (TIS) before any mass production can start. This paper aims to overcome some of these problems by using Finite Element Method (FEM) to study bottle mechanical properties, particularly maximum stress and deformation that can be employed to evaluate performance and optimal thickness. From simulation results the optimal thickness of a 6-liter bottle, that its maximum stress can still be kept under critical value, is 0.45 mm. The thinner and lighter bottle reduces the amount of material usage. The FEM simulation also speeds up and alleviates some necessary testing procedures in a prototype designing process.

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