Thermodynamic Analysis for Hybrid Low Temperature Sustainable Energy Sources in Cascade Heat Pump Technology (original) (raw)
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2017
The Cascade heat pump system is commonly used to overcome the high temperature lift problem of the system. In the present investigation eight refrigerant pairs were studied including R717/R134a, R410A/R134a, R407C/R134a, and R717/R600a, R744/R134a, R744/R290, R744/R600a, and R744/R717 at HT condenser of (70)°C and (75)°C. Hot water is to be produced at temperature range (60 to 65)°C with a proper flow demand. The evaporator temperature at the LT cycle side was ranged between (-10)°C and (-2)°C. The intermediate temperatures at the cascade heat exchanger were (20, 22.5, 33, and 35)°C depending on the refrigerant pairs implemented in the Cascade heat pump. Sea water at (7)°C was used as a sustainable low temperature heat source and 30% ethylene glycol-water brine as a thermal fluid carrier for heat extraction. The evaluation of the thermal performance of the refrigerant pairs was based on a fixed heat pump extraction load at the LT cycle evaporator. The R744/R134a and R744/R290 system...
International Journal of Economy, Energy and Environment, 2017
The present investigation deals with the performance assessment of Cascade heat pump plants. The overall power consumption for a Cascade system for typical heat pump characteristics was studied. Four environment friendly refrigerant pairs R717/R134a, R410A/R134a, R407C/R134a, and R717/R600a were investigated at low temperature cycle (LT) evaporator and high temperature cycle (HT) condenser temperatures of (-15 to-4)°C and (70)°C respectively. A preliminary heat pump plant is suggested to produce (500) kW heat output load as hot water demand at (65)°C with (25)°C temperature lift and a proper circulation rate. The investigation was carried out at cascade heat exchanger intermediate temperature (IT) of (33)°C and (35)°C. Sea water at (7)°C was used as a sustainable low temperature heat source and (30%) ethylene glycol-water brine at temperature of (5)°C as a thermal fluid heat carrier at the LT cycle evaporator. The evaluation of the thermal performance of the refrigerant pairs was based on a fixed heat pump extraction load at the LT cycle. The heat pump heating coefficient of performance (COP) revealed an increase fell within the range of (5-7.5)% higher than that of the plant heating COP value for the studied refrigerant pairs at the whole investigated operating conditions range. The higher IT exhibited the highest heat pump and plant heating COP than those at the lower value. R717/R600a showed the highest heating COP, lower power consumption and lower global warming potential (GWP) among other investigated refrigerant pairs. The power consumed by auxiliary pumps to circulate thermal fluid heat carriers through a heat pump may account to (4-4.5)% and (2-3)% of the extracted and output heating loads respectively, higher values could be expected for real plant. Two polynomial correlations for the assessment of the pumping power in terms of the extracted and output heating loads were derived from the present work.
Journal of Heat Recovery Systems, 1982
~ascading of vapour-compression refrigeration and heat pump systems to produce both cooling and heating for industrial applications is an interesting possibility. As a first step in this direction, a detailed thermodynamic analysis of an idealised hybrid systems is made for various combinations of working fluids R12 or R22 on the refrigeration system and RI 1, R21 or R12BI on the heat pump system. Charts and correlations are presented to facilitate the estimation of performance parameters such as COP, isentropic compression work and cooling and heating capacities. For the temperature ranges considered, overall COPs in the range of 9.5-4.0 can be achieved.
2017
This investigation represents a thermodynamic assessment of thermal performance optimization for a proper heat pump technology suitable for district hot water production at (6065) °C. The clean energy sources integrated with environment friendly refrigerants were studied to optimize and validate the use of Cascade heat pump technology at various configurations. Three pure, R744, R600a and R134a, and one azeotropic mixture R410A refrigerants were circulated at different cycle arrangements. Two Cascade systems (Three Cycles), single Cascade system (Two Cycles), and compound Cascade system (Three Cycles) were proposed for the present assessment. The low temperature cycle operated at evaporator temperature of (15 to -2) °C and the high temperature condenser was set at a temperature of (70) °C. The single Cascade heat pump circulating R410A/R134a and the two Cascade R410A/R717/R134a systems showed the best heating coefficient of performance (COP). The former refrigerant pair exhibited hi...
Energy, 2018
High-temperature heat pumps (HTHPs) based on vapour compression can be used for industrial low-grade waste heat valorisation, which can aid in mitigating climate change. Currently, the performance of HTHPs operating at high-temperatures lifts is limited; therefore, advanced configurations become an opportunity for their utilization. This paper presents an HTHP cascade with configurations of internal heat exchangers (IHXs) that uses low GWP refrigerants in both high-stage (HS) (HCFO-1233zd(E), HFO-1336mzz(Z), HCFO-1224yd(Z), and pentane) and lowstage (LS) (HFO-1234yf, HFO-1234ze(E), butane, isobutane, and propane) cycles. Prior to the analysis and presentation of results, an optimisation of the operating conditions is performed based on intermediate temperature and IHX effectiveness in both stage cycles. Results indicate that butane and isobutane appear to be the most convenient working LS fluids from the point of view of coefficient of performance (COP). The highest system performance is obtained using pentane and HFO-1336mzz(Z) in the HS cycle. Compared to third-generation refrigerants (HFC-245fa/HFC-134a), a slight COP improvement is obtained using HCFO-1233zd(E), and HCFO-1224yd(Z). A comparable or even lower volumetric flow rate at the HS compression suction is also observed. The use of pentane/butane achieved maximum COP (3.15), which is a 13% improvement compared to COP obtained when HFC-245fa/HFC-134a is employed. Highlights A high-temperature heat pump cascade with the IHXs is proposed and optimised. Synthetic and natural refrigerants with low GWPs are proposed for both stages. The higher effectiveness of both IHXs in similar proportions increases total COP. Pentane/butane presents maximum COP and minimum HCFO-1224yd(Z)/HFO-1234yf. A few refrigerant pairs are comparable with HFC-245fa/HFC-134a in the stages of .
International Journal of Green Energy, 2019
In this study, a comparative thermodynamic performance analysis of cascade system (CCS) for cooling and heating applications is presented and compared for different refrigerant couples. The CCS consists of the low-temperature cycle (LTC) and high-temperature cycle (HTC). The CO 2 was used as working fluid in LTC, whereas the HFE 7000, R134a, R152a, R32, R1234yf, and R365mfc refrigerants were used in HTC. The heating and cooling coefficients of performance (COP ht , COP cl) and exergy efficiency of CCS are investigated parametrically according to various factors such as the evaporator, condenser, and reference temperatures. After thermodynamic analyses are completed, the COP cl of CCS is obtained as 1.802, 1.806, 1.826, 1.769, 1.777, and 1.835 for CO 2-HFE7000, CO 2-R134a, CO 2-R152a, CO 2-R32, CO 2-R1234yf, and CO 2-365mfc refrigerant couples, respectively. Furthermore, the heat exchanger has the highest exergy destruction rate, whereas the expansion valves have the lowest of exergy destruction rate.
INMATEH Agricultural Engineering
In the paper we presented a comparative analysis of the effect of the refrigerant used on the operation and performance of a heat pump with water-water and heat regeneration. Various sensitivity studies are presented comparatively for some eco-friendly refrigerants (R290, R600a, R454C, R152a) and R407C. Based on the energetic analysis, the energy destruction and loss were estimated for each device, depending on the destination and the operating regime. Graphic and numerical results are presented. In conclusion, a comparative analysis of the defined performance coefficient based on energy and energetic efficiency is presented. The interest of the study is important due to the applicability of geothermal heat pumps in the field of air conditioning of residential and industrial buildings but also in agriculture for animal farms, for drying some agricultural products in a climate with controlled temperature and relative humidity, in addition the water can be used in summer for irrigation.
Thermodynamic Study of a Combined Power and Refrigeration System for Low-Grade Heat Energy Source
Energies, 2021
This study focuses on the thermal performance analysis of an organic Rankine cycle powered vapor compression refrigeration cycle for a set of working fluids for each cycle, also known as a dual fluid system. Both cycles are coupled using a common shaft to maintain a constant transmission ratio of one. Eight working fluids have been studied for the vapor compression refrigeration cycle, and a total of sixty-four combinations of working fluids have been analyzed for the dual fluid combined cycle system. The analysis has been performed to achieve a temperature of −16 °C for a set of condenser temperatures 34 °C, 36 °C, 38 °C, and 40 °C. For the desired temperature in the refrigeration cycle, the required work input, mass flow rate, and heat input for the organic Rankine cycle were determined systematically. Based on the manifestation of performance criteria, three working fluids (R123, R134a, and R245fa) were chosen for the refrigeration cycle and two (Propane and R245fa) were picked f...
SIMULATION OF THERMODYNAMIC ANALYSIS OF CASCADE REFRIGERATION SYSTEM WITH ALTERNATIVE REFRIGERANTS
The main aim of this project is to analyses the cascade refrigeration system by employing various alternative refrigerant pairs and choosing the best pair for higher temperature circuit (HTC) and lower temperature circuit (LTC). The analysis was done in various refrigerants pairs which are R134a/R23, R290/R23, R404A/R23, R407C/R23, R410A/R23, R134a/R508B, R290/R508B, R404A/R508B, R407C/R508B, R410A/R508B, R134a/R170, R290/R170, R404A/R170, R407C/R170 and R410A/R170. Assuming the degrees of sub cooling and superheating as 5°C and 10°C, respectively. The condenser temperature in higher temperature circuit (HTC) was varied from 30°C to 50°C and evaporator temperature in lower temperature circuit (LTC) was varied from -70 to -50°C. The intermediate heat exchanger temperature is about -20°C. Furthermore, the efficiencies of the compressors are assumed to be equal as 0.7. It has been found that the coefficient of performance (COP) of the cascade refrigeration system increases and the mass flow rate of higher temperature circuit increases, along with the work of compressor with rise in evaporator temperature for all refrigerant pairs. On the other hand, the COP of the cascade refrigeration system decreases and the mass flow rate of higher temperature circuit increases, also there is increase in work of compressor with increase in condenser temperature. Finally, the refrigerant pair R134a–R170 has the highest COP and lowest mass flow rate, while R404A–R508B has the lowest COP and highest mass flow rate.
International Journal of Refrigeration-revue Internationale Du Froid, 2019
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights Thermodynamic performance of a cascade refrigeration system was investigated. Three mixed refrigerants (R744/R1270, R744/RE170, R744/R717) were tested in both subcycles. Mixed refrigerants allow a better thermodynamic performance than pure fluids. R744/RE170 presented the greatest global COP, 2.34, for a fixed cooling rate of 100 kW. Exergetic efficiency increased up to 30% and refrigerant mass flow rate was reduced up to 34%.