Adsorption Air Conditioner Research Articles

Performance of an Adsorption Chiller Using Diesel Truck Exhaust: Effect of Operating Parameters

ABSTRACT In India, air conditioning is essential in the truck driver’s cabin during the summer. An air conditioning system powered by the vehicle’s engine adds to the engine’s workload, resulting in higher fuel demand and more emissions. An adsorption chiller that runs on engine exhaust is designed here to lower the interior temperature of a truck cabin to address the above-mentioned issue. Here, an adsorption air conditioner system’s effectiveness is forecast using a lumped analytical technique. During the adsorption process, heat from the adsorber bed is absorbed by cold water and released into the radiator. The desorber bed has been heated using hot water as a heat transfer medium from the engine exhaust heat. The analysis was carried out using the adsorption kinetic equation at adsorption equilibrium. The influence of inlet water flow rate, temperature and switching time (adsorber process to desorber process and vice versa) on adsorption chiller performance has been studied here. According to simulation results, the proposed adsorption chiller can be used to keep the driver cabin cool during summer for operational conditions adopted during the simulation. The adsorption air conditioner’s highest coefficient of performance (COP), as determined by this investigation, was found to be 0.214.

Experimental investigation of an adsorption air-conditioner using silica gel-water working pair

Compared to adsorption chiller, adsorption air-conditioner can get significant benefit of less cost and complexity when it directly provides chilled air for air-conditioning. Hence, adsorption air-conditioner is suitable for residential solar cooling application. A 3 kW adsorption air-conditioner using silica gel-water working pair is designed and manufactured and its performance is fully tested under different conditions. The experimental results show that cooling power and COP can reach 3.98 kW and 0.632, respectively, without obvious periodic fluctuation of chilled air outlet temperature and relative humidity. Smaller hot water flow rate can help to reduce unmatching between heating and cooling operation of adsorption bed. Optimal half cycle time of this adsorption air-conditioner is found to be 750 s. COP of adsorption air-conditioner is generally larger than that of adsorption chiller which provides chilled water because of higher evaporation temperature. Besides, cooling water outlet temperature can reach 39.9 °C which can meet the requirement of domestic hot water use. So that adsorption air-conditioner can be used for cooling and heating cogeneration in a residential solar cooling application and achieve good performance.

Feasibility of solar adsorption air-conditioning in the region of Biskra: Reflection on the government support for electricity bills

In this paper, the feasibility of solar adsorption air conditioning system in the region ofBiskra (Algeria) is studied. The main objective is to give a reflection on the current governmentsupport for electricity bills. A comparison between three air conditioning systems was made bytaking into account economic and environmental constraints: classical mono-split system (A),classical centralized air conditioning chiller (B) and solar adsorption system (C). In the context ofthe current government support for electricity bills, results show that system A is actually thebest choice from the total investment costs, electrical consumption and maintenance point ofview. This is observed even with the gain of the electrical consumption obtained in the case ofsolar adsorption air conditioner (C). From an environmental point of view, the system (C) is moreadvantageous than the classical systems (A) & (B) especially for its use of the solar energy, its lowelectrical consumption, low CO2 emissions and low heat rejected to the outside. It can beconcluded that the current state policy do not encourage the transition to the use of airconditioning systems operate by renewable energies. Thus, the redirection of the current supportfor electricity bills to the support of the investment cost of the solar adsorption air conditioner(C) will make it more competitive in the Algerian market. In this case, system (C) can replace, inthe long-term, the system (A) used actually.

Effect of Exhaust Gas Temperature on the Performance of Automobile Adsorption Air-Conditioner

An adsorption air conditioning unit of two beds was designed and built. Each bed was constructed from two concentric copper pipes sets, the length of the pipes in each set was 1500 mm pipe. The inner pipe was 50 mm in diameter while the outer pipe was of 100 mm diameter. The inside surface of the outer pipe and the outside surface of the inner pipe were covered by two active carbon layers which were separated from each other by a 5 mm space, to allow for methanol vapour penetration through the two layers. Each bed was inserted in a metal pipe to convey the hot stream of exhaust gases, to form a two passes heat exchanger. To complete the adsorption air conditioner cycle, an evaporator and condenser were connected to the two beds. Exhaust gases were produced by a propane burner, which can be adjusted to deliver hot gases at a temperature range of 80 to 140°C. The work showed that there was direct relationship between the hot gas temperatures that was used to heat the bed and the chilled water temperature. When the hot gases temperature exceeded 120°C, the whole cycle time increased along with a slight increase in chilled water temperature with a reduction in COP. A minimum chilled water temperature of 7.6°C was obtained. This chilled water was supplied to a fan coil unit to maintain an inside temperature of 24.2°C for a 600 Watt conditioned space load. The maximum cycle COP was about 0.31 when the hot gas temperature was 120°C.

Study on gradient thermal driven adsorption cycle with freezing and cooling output for food storage

An gradient thermal driven adsorption cycle powered by low grade heat, such as geothermal, solar energy, or waste heat from factories, is constructed for the food storage both under the conditions of freezing (around −15 °C) and the refrigeration (around 5 °C). The cycle is combined by the CaCl2–BaCl2 adsorption freezer (first stage) and silica-gel/lithium chloride adsorption air conditioner (second stage) and it is driven by the heat source with gradient temperature that is lower than 100 °C.The cycle produces cooling and freezing power simultaneously with the implementations of adsorption and resorption processes. In the experiments the heat source temperature ranges from 70 to 90 °C, condensing temperature is controlled at 25 °C. The results show that thermal coefficient of performance (thermal COP) of gradient thermal driven cycle ranges from 0.13 to 0.28, which improves 87% compared with the adsorption freezing cycle under the heat source of 90 °C and evaporating temperature of −15 °C. The refrigerating capacity is 4.56 kW under driving heat source at 70 °C and the improvement is 76.5% if the heat source temperature increases to 90 °C. The exergy efficiency of the cycle are calculated to be 0.11–0.13 under the above conditions, and the exergy efficiency for heat utilization varies from 0.31 to 0.42, which is improved 90.3% and 75.6% compared with the adsorption freezing cycle and adsorption cooling cycle, respectively when the heat source temperature is 90 °C.

Performance improvement by mass-heat recovery of an innovative adsorption air-conditioner driven by 50–80 °C hot water

The processes of mass recovery and heat recovery in one micro-porous silica gel–water solar adsorption air conditioner were investigated. The influences to MH recovery (mass–heat recovery) performances under different working conditions were studied. The result shows when the hot water temperature is lower, longer mass recovery time is needed for the re-adsorption of the cold adsorbent bed and re-desorption of the hot adsorbent bed. Meanwhile, the process of heat recovery can recover heat to improve Coefficient of Performance (COP) of the system. When the hot water inlet temperature (Th,i), cooling water inlet temperature (Tc,i) and chilled water outlet temperature (Tch,o) are about 55 °C, 26 °C, 16 °C, the COP is 0.31 in the cycle with 180 s of mass recovery while the COP is 0.27 in the cycle with 90 s of mass recovery. When the Th,i, Tc,i and Tch,o are 80 °C, 30 °C and 15 °C, the cooling capacity and COP are 15.3 kW and 0.5 in the cycle without heat recovery, while in the cycle with 30 s of heat recovery, the cooling capacity, COP and specific volumetric power can arrive 15.8 kW, 0.53 and 20.6 kW m−3.

Development and lab-test of a mobile adsorption air-conditioner

This paper is focused on the description of a mobile adsorption chiller for cooling in a truck cabin and its experimental performance. The prototype, designed and built at CNR – ITAE, consists of a double-bed adsorber connected with an evaporator and a condenser and driven by the low grade thermal energy coming from the engine coolant loop. Overall volume and weight of the machine are 170 dm3 and 60 kg, respectively. Performance assessment was preliminarily carried out at ITAE laboratory under the typical EU car air conditioning conditions. The experimental results obtained showed that the system is able to deliver an Average Cooling Power ACP = 1–2.3 kW and a Cooling COP = 0.25–0.45, at a desorption temperature of about 90 °C (Tev ∼ 8–14 °C and Tcon ∼ 28–35 °C). Afterwards, the cooling system was integrated in a real truck cabin (IVECO STRALIS) and tested on a laboratory test bench, where the engine cooling loop was simulated through an ideal heat source, so demonstrating that the chiller is able to provide cooling comfort to the passengers.

Adsorption Refrigeration: A Survey of Novel Technologies

The adsorption refrigeration is based on the evaporation and condensation of a refrigerant combined with adsorption or chemical reaction. The soaring fossil fuel price and the awareness of environmental problems offer many potential applications to thermal powered adsorption cooling. However, the adsorption cooling machines still have some disadvantages that hinder their wide application. This paper reviews more than 100 patents filed mainly since year 2000 that propose technologies to improve adsorption system and make it become a realistic alternative. The patents surveyed are classified into four main groups: adsorption system development, adsorbent bed innovation, adsorbent/adsorbate material development and novel application of adsorption cooling system. The various technology options are discussed and evaluated. “Hot spots” and key inventors/applicants are identified. An assessment is made about current and future development of adsorption refrigeration technologies. Keywords: Adsorption refrigeration, Adsorption air-conditioner, Adsorption cooling, Adsorption chiller, adsorption heat pump

06/02220 Design and performance prediction of a novel zeolite-water adsorption air conditioner: Wang, D. C. et al. Energy Conversion and Management, 2006, 47, (5), 590–610.

The geometric structures and fractal dimensions of fractal tree-like branched networks have the significant influence on the efficiency of physiological, communication and transport processes. We analyze the heat conduction through symmetric fractal tree-like branched networks. We obtain the expression of thermal conductivity in the networks and analyze the relationship between the effective thermal conductivity (ETC) and the geometric structures of the networks. We have found that the ETC of the networks is always less than that of a single channel, and the value of the thermal conductivity of the network can tend to zero under certain conditions; as long as the branching number N is fixed, the heat conduction reaches the fastest rate at the same diameter ratio βm which is corresponding to the fractal dimension Dd = 2.0. We have also found that the heat conduction in the networks is rather different from Murray’s law both for laminar regime (2−1/3) and for turbulent flow regime (2−3/7).

Automotive Adsorption Air Conditioner Powered by Exhaust Heat. Part 1: Conceptual and Embodiment Design

The significant power used by the mechanical compressor of an automobile (12-17 per cent during commuting for subcompact to mid-size cars) can be eliminated by powering the air conditioner with otherwise wasted exhaust heat. In the present work the conceptual and embodiment design of an exhaust-powered adsorption (desiccant-vapour) air conditioner are traced. The design is preceded by detailed discussion of automotive cooling requirements and the typical driving scenario on which the design is based. Adsorption cooling is then compared with other thermally powered cooling technologies [Stirling, absorption (liquid-vapour), and thermoelectric (i.e. Peltier)], demonstrating that adsorption is the best alternative in terms of size and mass. Next are described inventions to boost specific cooling power (SCP) in kW cooling per kg of air conditioner beyond the state of the art described in the literature while maintaining an adequately high coefficient of performance for cooling (COPc). The adsorbent is heated and cooled by light oil which in turn is heated and cooled by exhaust and fresh air. Such indirect heating and cooling achieves the required COPc, permits optimum placement of components in the vehicle, and allows the use of phase-change material (e.g. wax) to store exhaust heat, shortening the time needed to recharge the refrigerant reservoir which provides immediate cooling after start-up of a cold engine.

Automotive Adsorption Air Conditioner Powered by Exhaust Heat. Part 2: Detailed Design and Analysis

This paper presents the detailed design and analysis of an automotive adsorption air conditioner, particularly the critical components, the adsorbent canisters, or adsorbers, and the exhaust-to-oil heater. The best adsorbent-refrigerant combination is activated carbonammonia. For the adsorber shell and tubes, austenitic stainless steel 304 has sufficient fatigue strength at 300 °C and is compatible with ammonia. Annular fins and wool inside the adsorbers are nickel-plated low-carbon steel. The exhaust-to-oil heater is of ferritic stainless steel and can withstand heating beyond 400 °C. The adsorbers, oil heater, and refrigerant reservoir are sized on the basis of the cooling requirement for a subcompact car during a typical commute, as defined in Part 1. The refrigerant reservoir provides immediate cooling upon start-up of a cold engine while the exhaust system and adsorbers are heating. A thermal reservoir containing phase-change material (PCM) allows full recharging of the refrigerant reservoir after a 20 min commute. Detailed thermal, fluidic, and mechanical analyses of the adsorbers and oil heater are performed. Eliminating the mechanical compressor increases fuel mileage by 14-18 per cent for mid-size, compact, and subcompact cars, or 4.6-6.0 per cent annually, given a 4 month cooling season. The adsorption system adds ∊3.5 per cent to vehicle mass, which reduces fuel mileage by ∊2.1 per cent. Thus, the annual benefit/cost ratio in terms of fuel mileage ranges from 2.3 to 2.7.

Operational aspects of adsorption air-conditioner used in diesel locomotive

A locomotive cabin adsorption air-conditioner has been equipped in #DF4B-2369 locomotive; and has been successfully run for 2 years. It is powered by waste heat from the exhaust of the diesel engine. The influence on heat transfer is described by the equivalent heat transfer coefficient or thermal resistance of components inside the adsorber. The variation of adsorption capacity is expressed by a non-equilibrium adsorption function. The dynamic heat transfer process of adsorption air-conditioning system is treated with the lumped parameter method. Some typical running experimental results are present. The diesel engine rotating speed and locomotive speed influenced on the refrigeration system are discussed. The maximum mean refrigeration power is regarded as an objective function. Based on experiments and theoretical analysis, the running characteristics of the air-conditioning system are optimized. Some techniques of performance improvement are suggested as well. Copyright © 2006 John Wiley & Sons, Ltd.

Design and performance prediction of a novel zeolite–water adsorption air conditioner

Abstract A novel adsorption air conditioner is designed that supplies 8–12 °C chilled water for the fan coil in the locomotive operator cabin. Different from other two-bed adsorption cooling systems, this system has two adsorption/desorption chambers. One adsorber, one condenser and one evaporator are housed in one and the same adsorption/desorption chamber. There are no valves installed in the vacuum side. So, the reliability of the system is improved greatly. This machine uses zeolite and water as the working pairs. This system is driven by 350–450 °C exhaust gas generated by the internal combustion engine of the locomotive. The designed refrigerating power and COP (coefficient of performance) are 5 kW and 0.25, respectively, according to the requirements for the refrigeration output in the locomotive operator cabin and the waste heat provided by the engine. In this paper, a model for this system is described, and the simulation results are discussed. The model is validated in principle by limited experimental data. According to the calculation results, the refrigerating power of the machine is up to 10 kW with gas inlet temperature of 450 °C and evaporating temperature of 6.5 °C. The adsorber can be heated from 97 °C to 423 °C or cooled from 423 °C to 97 °C in 1320 s. Therefore, the heat and mass transfer performance of the adsorber is improved greatly. A few experimental data prove these conclusions.

04/00459 Locomotive driver cabin adsorption air-conditioner: Jiangzhou, S. et al. Renewable Energy, 2003, 28, (11), 1659–1670.

04/00459 Locomotive driver cabin adsorption air-conditioner: Jiangzhou, S. et al. Renewable Energy, 2003, 28, (11), 1659–1670.

Practical experiments on an adsorption air conditioner powered by exhausted heat from a diesel locomotive

Experimental studies on the practical performance of an adsorption air conditioning system powered by exhausted heat from a diesel locomotive are presented. The system incorporates one adsorbent bed and utilizes zeolite–water as a working pair to provide chilled water for conditioning the air in the driver’s cab of the locomotive. Performance tests under different running conditions have been carried out. Experimental results show that the suggested adsorption system is technically feasible and can be applied for space air conditioning of the locomotive driver’s cab, except the case when the locomotive tracts a way train. The average refrigeration power ranging from 3.0 to 4.2 kW has been obtained under typical running conditions.

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. The present locomotive driver cabin air-conditioners usually use alternating current to drive the piston refrigeration compressors whose refrigerants are R12 or R22. The COP of the system is low. The refrigerant leaks easily. The internal combustion engine generator can only provide direct current, which is converted into alternating current by an inverter. A great deal of diesel oil has to be consumed to generate electricity. The inverter is complex in structure, with low reliability, and high cost. This paper presents a novel adsorption air-conditioning system used in internal combustion engine locomotive driver cabin. This system employs the zeolite-water as working pairs and is driven by the waste heat from exhaust gas of internal combustion engine. This new system consists of an adsorber and a cold storage evaporator, then the refrigeration capacity can be continuously and steadily provided to the locomotive driver cabin for space cooling instead of the electric vapor compression air-conditioning system. Experiments and prototype machine operation showed that this new type of system could meet the demands of air conditioning for locomotive driver cabin. This paper presents some results of experiment and prototype systems. The characteristics of system are discussed as well.

Adsorption cold storage system with zeolite–water working pair used for locomotive air conditioning

Adsorption cold storage has lately attracted attention for its large storage capacity and zero cold energy loss during the storing process. Thermodynamic and experimental studies on the cold storage capacity and the cold discharging process, in which the adsorber is either air cooled or adiabatic, have been presented. An adsorption cold storage system with zeolite–water working pair has been developed, and some operating results are summarized. This system is used for providing air conditioning for the driver’s cab of an internal combustion locomotive. Unlike a normal adsorption air conditioner, the system starts running with the adsorption process, during which the cold energy stored is discharged, and ends running with the generation process. The adsorbent temperature decreases during the cold storing period between two runs. The refrigeration power output for the whole running cycle is about 4.1 kW. It appears that such a system is quite energetically efficient and is comparatively suitable for providing discontinuous refrigeration capacity when powered by low grade thermal energy, such as industrial exhausted heat or solar energy.

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.

Study on heat and mass recovery in adsorption refrigeration cycles

An adsorption air conditioner has been developed and some operation results are summarized. Mass recovery process is proposed to improve the performance. Performance predictions are presented and show that mass recovery can play an important role to better the performance of adsorption refrigeration cycle. Coefficient of performance might be increased or decreased with mass recovery process due to different working conditions. Cooling capacity can be significantly increased with mass recovery process. The cycle with mass and heat recovery has a relatively higher improvement. It can also be seen that the cycle time will be much shorter and it will certainly enhance the cycle with higher cooling/heating power.