Y.X. Xu

An energy efficient hybrid system of solar powered water heater and adsorption ice maker

A new hybrid system of solar powered water heater and adsorption ice maker has been proposed. The working principle of the combined cycles of solar refrigeration and heating is described, theoretical simulation to the thermodynamic processes has been made. Experiments have been performed in a developed prototype hybrid system; it is verified that the hybrid system is capable of heating 60 kg water to about 90°C as well as producing ice at 10 kg per day with a 2-m2 solar collector.

Experimental study on dynamic performance analysis of a flat-plate solar solid-adsorption refrigeration for ice maker

A flat-plate solid-adsorption refrigeration ice maker has been built for demonstration purposes. The working pair consists of methanol used as the refrigerant and activated carbon as the adsorption medium. The adsorbent bed is constructed of two flat-plate collectors, with a total surface area of 1.5 m2. Solar radiation can be simulated with quartz lamps and some important parameters such as temperature and pressure of each subsystem can be handled by a computer. The experimental results show that this machine can produce 4–5 kg of ice after receiving 14–16 MJ of radiation energy with a surface area of 0.75 m2, while producing 7–10 kg of ice after receiving 28–30 MJ of radiation energy with 1.5 m2. These are the most advanced results for a solar ice maker so far. All these successful achievements will speed up the commercial processing of a solar ice maker.

Performance researches and improvements on heat regenerative adsorption refrigerator and heat pump

Abstract A heat regenerative adsorption refrigerator using spiral plate heat exchangers as adsorbers and an adsorption heat pump for air conditioning using plate fin heat exchangers or plate fin shell and tube type heat exchangers as adsorbers have been developed and researched. Experimental research results are shown. The activated carbon–methanol adsorption pair is used for the two kinds of adsorption systems. With a heat source temperature of 100°C, the refrigerator achieved a refrigeration power density of more than 2.6 kg ice per day per kg activated carbon with a coefficient of performance (COP) of 0.13, and the heat pump achieved 150 W/kg activated carbon for air conditioning with a COP of about 0.4.

Study of the performance of activated carbon-methanol adsorption systems concerning heat and mass transfer

Abstract Three types of adsorbers and two types of activated carbon–methanol adsorption systems are studied, and the structure of adsorbers, performance of adsorbents, performance of different adsorbers and different systems are compared. Results show that the heat transfer coefficient of solidified bed are much higher than that of granular bed, the design of gas flow channels in adsorbers is very important to the performance of mass transfer and the performance of the whole system. Performance of the adsorber with good design of gas flow channels is much better than that of other two types of adsorbers.

Experimental study of a solidified activated carbon-methanol adsorption ice maker

Abstract In this paper, the experiments are performed on an adsorption ice maker driven by waste heat, which uses up to two beds. Each bed uses methanol as refrigerant and solidified activated carbon (120 kg adsorbent totally, 60 kg adsorbent per bed) as adsorbent. This system is designed to be driven by the waste heat of a 100 kW diesel engine. The experiments show that the cooling power could be enhanced by the mass recovery process up to 11%, and the heating power could be lowered by the heat recovery process up to 30%. The optimal cooling power of this prototype is about 2.0 kW and corresponds to a specific cooling power (SCP) is about 17 W/kg with both heat and mass recoveries between two beds. Considering the optimal adsorption time is much longer than optimal desorption time at the condition of ice making, the experiments are operated on a single bed (60 kg adsorbent per bed) and the adsorption time used in experiments is two times of desorption time, then the performance of a three-bed adsorption ice maker (120 kg adsorbent totally, 40 kg adsorbent per bed) is predicted by the results of experiments on this single bed. The results of prediction show that both COP and cooling power of three-bed operation could be enhanced greatly compared to the two-bed operation; optimal SCP and COP are respectively 22 W/kg and 0.239 when mass and heat recoveries proceed between three beds. Optimal ice productivity of this three-bed system is 21 kg/h when the water temperature is 25 °C and ice temperature is −7 °C.

Experiment on a continuous heat regenerative adsorption refrigerator using spiral plate heat exchanger as adsorbers

Spiral plate heat exchangers were proposed to be used as adsorbers, and a prototype heat regenerative adsorption refrigerator using the activated carbon-methanol pair was developed and tested. The adsorption system using 12 kg activated carbon has a cycle time of 40 min., meanwhile 14 kg ice per day was made.

Study of a solar powered solid adsorption–desiccant cooling system used for grain storage

A hybrid solar cooling system, which combines the technologies of rotary desiccant dehumidification and solid adsorption refrigeration, has been proposed for cooling grain. The key components of the system are a rotary desiccant wheel and a solar adsorption collector. The former is used for dehumidification and the later acts as both an adsorption unit and a solar collector. The heating load from sunshine can thus be reduced to a greater extent since the solar adsorption collector is placed on the roof of the grain depot. Compared with the solid adsorption refrigeration system alone, the new hybrid system performs better. Under typical conditions, the coefficient of performance of the system is >0.4 and the outlet temperature is <20°C. It is believed that the system can be used widely in the regions with abundant solar resources due to such advantages as environmental protection, energy saving and low operation costs. Additionally, some parameters, for example, ambient conditions, the effectiveness of the heat exchanger and evaporative cooler, mass air-flow rate, etc., which affect system performance, are also analyzed.

Experimental investigations on adsorption air-conditioner used in internal-combustion locomotive driver-cabin

An internal-combustion locomotive driver-cabin adsorption air-conditioner is a new type of space cooling system, which employs zeolite-water as working pairs and is driven by the waste heat from the exhaust gas of internal-combustion engines. Experiment methodology of this air-conditioner is presented and the results and their impact factors are discussed. Refrigeration output performances under adiabatic and cooling conditions are analyzed as well.

Locomotive driver cabin adsorption air-conditioner

Drivers can easily feel fatigue and aprosexia due to the high temperature inside the locomotive driver cabin in summer. The current locomotive driver cabin air-conditioning system cannot meet the needs of operating condition and environmental protection. It is a very urgent task to develop an air-conditioning system which is suitable for application in internal combustion engine locomotive driver cabin.

Research on a combined adsorption heating and cooling system

Abstract A combined cycle capable of heating and adsorption refrigeration is proposed, and the experimental prototype has been installed. The system consists of a heater, a water bath, an activated carbon–methanol adsorption bed and a ice box. This system has been tested with electric heating, and has been found that with 61 MJ heating, the 120 kg water in the bath can be heated up from 22 to 92 °C meanwhile 9 kg ice of −1.5 °C is made. The calculated COP system is 0.0591 and COP cycle is 0.41. After reconstruction to a real hybrid household water heater–refrigerator, when 55 MJ heating is added to 120 kg 21 °C water, and the condensing temperature is controlled at about 30 °C, the result is the 4 kg water contained inside the methanol refrigerant evaporator was iced to −2 °C, the cooling capacity of the ice and the refrigerant in the evaporator will maintain the 100 l cold box for about three days below 5 °C. The experiments show the potentials of the application of the solar powered hybrid water heater and refrigerator. Theoretical simulation has been done, which is in good agreement with experimental results. This research shows that the hybrid solar water heating and ice making is reasonable, and the combined cycle of heating and cooling is meaningful for real applications of adsorption systems.