Thermostat Settings Research Articles

A rapid method to detect Cryptolestes ferrugineus (Coleoptera: Cucujidae) larvae in stored grain

Modifications of three detection methods, based on the heat-gradient principle employed by the Berlese funnel method were investigated to extract larvae of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), developing under the seed coats of infested kernels in grain samples. One-kilogram samples of wheat, barley and corn were artificially infested with rusty grain beetle eggs, resulting in survival rates (to larval stage) of 71.1 ± 14.4, 58.9 ± 14.3, and 24.7 ± 11.8%, respectively. Sets of 10 infested kernels containing different-aged larvae (10 individuals × 4 instars) were added to 1-kg samples of hydrated grain, then heated on screens beneath heat sources (lights) at several heights in three different containers (Berlese funnel, with a 7-cm-deep grain layer, or square and rectangular screened boxes with a grain layer several kernels deep). There were no significantly different extraction rates between the rectangular and square containers for all heating trials. A larval extraction rate of 31% was produced by 1-h trials with wheat (15% moisture content wet basis) 5.5 cm below the lamp bank with a thermostat set at 50°C. This matched the efficiency of the Berlese funnel method (36% extraction in 6 h), but in much less time. Similar results were found for barley, bu t for corn the square and rectangle gave significantly better extraction than the Berlese funnel, although extraction efficiency was half that of wheat and barley. Considerably lower extraction rates were obtained from trials that did not use a thermostat. The results from this experiment show that there is a potential alternative detection method with the thermostatically controlled heating of a thin layer of grain that should be faster than the conventional 6-h Berlese funnel method. Key words: Cryptolestes ferrugineus, grain, larval extraction, Berlese funnel, grain monolayer

Role of ambient temperature, door opening, thermostat setting position and their combined effect on refrigerator-freezer energy consumption

Refrigerator-freezers energy consumption is greatly affected by room temperature, door opening and thermostat setting position. Two frost free household refrigerator freezers of the same capacity were tested in the laboratory to determine the sensitivity of their energy consumption to various usage conditions. The experiments were conducted to investigate the effect of single variables, such as temperature, thermostat setting positions and door opening, and their combined effect on energy consumption. Our investigation reveals that room temperature has the higher effect on energy consumption, followed by door opening. Thermostat setting position has the lower effect on energy consumption. More detailed tests were performed under different room temperature, thermostat setting position and door opening conditions. With the experimental results, a first order mathematical model has been developed to investigate their combined effect on energy consumption. The test results are discussed and presented.

Modelling and simulation of an absorption solar cooling system for Cyprus

In this paper a modelling and simulation of an absorption solar cooling system is presented. The system is modelled with the TRNSYS simulation program and the typical meteorological year file containing the weather parameters of Nicosia, Cyprus. Initially a system optimisation is carried out in order to select the appropriate type of collector, the optimum size of storage tank, the optimum collector slope and area, and the optimum thermostat setting of the auxiliary boiler. The final optimised system consists of a 15-m 2 compound parabolic collector tilted 30° from the horizontal and a 600-l hot water storage tank. The collector area is determined by performing the life cycle analysis of the system. The optimum solar system selected gives life cycle savings of C£1376 when a nonsubsidized fuel cost is considered. The system operates with maximum performance when the auxiliary boiler thermostat is set at 87°C. The system long-term integrated performance shows that 84,240 MJ required for cooling and 41,263 MJ for hot water production are supplied with solar energy.

The applicability of ISO household refrigerator–freezer energy test specifications in Malaysia

ISO 8187, ISO 8561, and ISO 7371 are the relevant test standards for household refrigerating appliances. This paper presents the possibility of introducing ISO household refrigerator–freezer test standards in Malaysia. An experiment was conducted to investigate the effect of room temperature, door opening, thermostat setting position, relative humidity, and loading on energy consumption of a household refrigerator–freezer. With the experimental data, a multiple regression equation is developed to investigate their combined effect. Finally, energy consumption according to the regression equation with optimum setting conditions is compared with ISO standard test conditions. Our comparison reveals that ISO refrigerator–freezer test standards are applicable with respect to Malaysian climatic conditions and usage patterns.

Phosphine as a replacement for methyl bromide for postharvest disinfestation of citrus

Abstract Methyl bromide is the only fumigant registered for disinfestation of citrus in Australia. However, it has been identified as an ozone-depleting chemical and its use is being restricted in accordance with an international agreement. The only alternative to a 2-h methyl bromide fumigation is cold treatment at 1°C for 16 days, and a more rapid alternative is desirable. The phosphine cylinder gas formulation ECO2FUME (phosphine with CO2 as a carrier gas) was recently registered for 15-h fumigation of cut flowers. This treatment was used as a basis for experimental fumigations of oranges infested with larvae of Queensland fruit fly, Bactrocera tryoni in a 900-l chamber. Uninfested oranges were included in all fumigations to check for possible adverse effects. A 16-h fumigation at 20°C with an initial phosphine concentration of 0.98 g m−3 resulted in 96.4% mortality of fly larvae. This was a promising result but the mortality achieved was insufficient to meet mortality requirements for interstate (99.5%) or export trade (99.9%). Exposure times, temperatures and phosphine concentrations were all increased in subsequent fumigations. In the final series of fumigations with export grade Washington Navel oranges the exposure time was 48 h, thermostat settings for the chamber heater were 23 or 25°C, initial phosphine concentrations were 1.67 g m−3 and the concentrations were topped up to ∼0.7 g m−3 after 24 h. No adverse effects on the oranges were observed, and a mortality of 99.998% was achieved with >48 000 larvae exposed. This would meet requirements for interstate trade and possibly also some international trade, particularly if incorporated as part of a systems approach.

AERATION STRATEGIES FOR PREVENTING SPOILAGE OF WHEAT STORED IN TROPICAL AND SUBTROPICAL CLIMATES

The research objective was to determine the best airflow rates and fan control methods for preventingspoilage of aerated wheat stored in round bins and large horizontal storages under tropical and subtropical climaticconditions. The best aeration strategies were determined for eight Brazilian locations based on the simulated results ofover drying costs, deterioration, and electrical energy to operate the fan using 10 years of weather data. The computermodel simulated one-dimensional forced convection using a non-equilibrium model, heat conduction in the direction ofthe airflow for periods without ventilation, and grain deterioration during the storage period. The least cost fan controlmethod for wheat aeration was a differential thermostat that operated the fan according to the difference between theaverage grain temperature and the dry bulb temperature of the outside ambient air. The best aeration conditions withgrain at 13% initial moisture content were a differential thermostat setting between 5 and 7C, a linear airflow ratebetween 1 and 3 L s1 m3, and an air temperature increment between 1 and 5C. The maximum allowable storage timesfor storing aerated wheat at 13% initial moisture content in round bins were Curitiba (12 mo), Porto Alegre (11 mo), SoPaulo (10 mo), Belo Horizonte (9 mo), Goinia (8 mo), Florianpolis (8 mo), Campo Grande (7 mo), and Cuiab (4 mo).These maximum times correlated fairly well with the annual average time that the ambient air temperature was below15C. The maximum allowable storage time was up to 3 mo shorter for horizontal grain storage structures than for roundbins.

Estrogen and Bone-Muscle Strength and Mass Relationships

The largest voluntary loads on bones come from muscles. To adapt bone strength and mass to them, special strain threshold ranges determine where modeling adds and strengthens bone, and where remodeling conserves or removes it, just as different thermostat settings control the heating and cooling systems in a house. If estrogen lowers the remodeling threshold, two things should occur. First, at puberty in girls, bone mass should begin to increase more than in boys with similar muscle strengths, owing to reduced remodeling-dependent bone losses, while gains from longitudinal bone growth and bone modeling continue normally. That increase in bone mass in girls should plateau when their muscle strength stops increasing, since their stronger bones could then reduce bone strains enough to turn modeling off, but could let remodeling keep conserving existing bone. Second, decreased estrogen secretion [or a related factor(s)], as during menopause, should raise the remodeling threshold and make remodeling begin removing that extra bone. That removal should also tend to plateau after the remaining and weaker bone lets bone strains rise to the higher threshold. Postmenopausal bone loss shows the second effects. Previously unremarked relationships in the data of a 1995 Argentine study showed the first effects. This supports the idea that estrogen can affect human bone strength and mass by lowering the remodeling threshold, and loss of estrogen would raise the threshold and help cause postmenopausal bone loss even if other factors help to do it. The Argentine study also suggested ways to study those things and the roles of muscle strength and other factors in controlling bone strength and mass in children and adult humans. Those factors include, in part, hormones, vitamins, calcium, diet, sex, race, age, medications, cytokines, genetic errors, gene expression patterns, and disease.

Comparison of Peanut Dryer Control Strategies1

Abstract Peanuts were mechanically cured from field moisture contents ranging from 11.5 to 32.8% wet basis to levels acceptable for marketing (< 10.5%) using two dryer control strategies. The first control algorithm consisted of a constant thermostat setting of 39 C, while the second required manual thermostat control on an hourly basis such that the minimum plenum relative humidity was between 40 and 60% and the maximum plenum temperature was less than 39 C. The average drying rate using the variable thermostat set point (0.3%/hr) was half that obtained with the constant set point (0.6%/hr). Average curing time for the variable thermostat setting was 56% longer than for the peanuts cured using the constant thermostat. Fuel consumption was reduced by approximately 30% using the variable set point. Kernel size distributions and milling quality indicated by bald kernels were significantly better (P ≤ 0.1) for peanuts cured using the variable thermostat control. Increasing available dryer capacity by 40% would allow the buying point manager to handle the same amount of peanuts during the same harvest interval. Economic analysis showed that the annual capital cost for additional drying equipment could not be offset by energy savings alone. Based on increased shelled product value and energy savings, shellers could realize an increase in net revenue of approximately $14/1000 kg of farmers stock peanuts by using a variable thermostat set point.

A model of the domestic hot water load

The electrical load required to supply domestic hot water is an important load for two reasons: (1) it represents a large portion (30 to 50%) of the domestic load; and (2) it is a load which can easily be controlled by the consumer or the supplier, because the use of the hot water need not coincide with the heating of hot water. A model representing the power system load due to hot water consumption from storage water heaters is provided. Variable parameters include the average amount of water used, the mean and deviation of distributions of usage times, thermostat settings, inlet water temperature and electrical heating element ratings. These parameters are used to estimate the after diversity electricity demand profile, and were verified for accuracy by comparison with measurements. This model enables the prediction of the effects of load control, examples of which are given in this paper. The model is also useful for evaluation of the response which could be expected from demand-side management options. These include changing the size of heating elements, reduction in water consumption and reduction in thermostat settings.

Cold Hands, Warm Hearth?: Climate, Net Takeback, and Household Comfort*

Insulation reduces marginal heating cost and may lead to a takeback effect of higher wintertime thermostat settings, with a consequent dilution of energy savings. Alternatively, additional insulation could permit a lower thermostat setting by reducing drafts and radiation while increasing moisture retention, thereby enhancing comfort. This paper evaluates thermostat net takeback, the difference between takeback and enhanced comfort. Evidence supports the existence of both effects, with net takeback at the low end of literature estimates. Net thermostat takeback is on the order of 0.05 degrees F, leading to an energy takeback that ranges from 1-3% of potential energy savings, depending on climate and house size. Other significant determinants of thermostat are heating energy price and the presence of elderly or young occupants.

Theoretical current and future indoor thermal preferendum for equatorial western and tropical South Pacific

Current and future indoor thermal preferendum are estimated for a number of locations in the equatorial western and tropical South Pacific region. Current warm season mean monthly temperatures, for the majority of the study area, are in excess of predicted indoor thermal preferendum, indicating the need for either passive, or active cooling, of indoor environments. Comparison of accepted warm season thermostat settings, with theoretical preferred indoor temperatures, suggests that current indoor environments may be over airconditioned. Climatic change will lead to a divergence of environmental and preferred indoor temperatures. As a consequence, increased levels of airconditioning may be required. The possible energy savings that may result, due to the application of location specific thermostat settings, in line with preferred indoor thermal preferendum, are discussed for a Greenhouse forced warmer western equatorial and tropical South Pacific.

Reducing Mixing Fan Thermostat Setpoints in Naturally Ventilated Broiler Housing During Hot Weather

Performance of poultry during hot weather has been improved by reducing the air temperature and increasing air movement over the birds during the coolest portion of a diurnal cycle. The purpose of this study was to evaluate effects of increasing the use of mixing fans at night during hot weather in naturally ventilated houses on four broiler farms. Mixing fan thermostats wee set according to the standard policy of the cooperating company in the control houses and 5 or 10°F lower in the test houses. When thermostat settings were reduced by 10°F for summer flocks in 1991 and 1992, several results appeared: average weight gain was 0.02 to 0.18 lbs greater, feed conversion ratio was 0.01 to 0.04lb/lb lower, and mortality was 0.2 to 1.2% lower in the test houses than in the control houses. Based on electricity and production costs, the net benefit to the grower varied from $25 to $275 per house for these summer flocks. For flocks that extended into the fall of 1992, there was little effect on feed conversion or livability, so the growers experienced net losses averaging $96 per house.

Scalding Water Temperatures

Tap water scald burns are the most frequent cause of nonfatal burn injuries in United States children. Most of these burns occur in the home, and hot water heater thermostat settings below 60°C (140°F) significantly decrease the risk of such burns in young children. The American Academy of Pediatrics and other safety-promotion organizations recommend that thermostats be set at 49 to 53°C (120 to 130°F), and ordinances encouraging lower hot water temperatures exist in some localities. We advise our pediatric colleagues that consumer products manufacturers do not always follow these recommendations in their published guidelines for product use. Specifically, we have found that four of five major manufacturers of automatic dishwasher detergent recommend hot water thermostat settings of 60°C or higher. (See Table.)

Electricity consumption in manufactured housing

This paper gives empirical results regarding the determinants of electricity consumption in manufactured housing, commonly called mobile homes. The data consist of a random sample of over 400 Florida electricity consumers - with information on socioeconomic characteristics, housing features and monthly kWh consumption. The model explains over 40% of the variation between customer usage, with signs and sizes of various coefficients fitting economic theore. The results for thermostat settings, site orientation and conservation investments are particularly interesting.

Preventing tap water scalds: do consumers change their preset thermostats.

One goal of the regulatory approach to tap water scald prevention is the installation of hot water heaters at thermostat settings considered safe. In this strategy, it is assumed that consumers will not change preset thermostat settings, an assumption evaluated in a study of 62 families. It was found that 60% of the sample did not change their preset thermostats. Surprisingly, some of those families (27%) who did not increase their settings still had unsafe (> 54 degrees C) water temperatures.

Older adults: clothing preferences for thermal comfort in cold weather

Escalating energy prices and widely publicized energy saving practices in the last decade have induced some older consumers to lower household temperatures during cold weather. Therefore, the effective manipulation of clothing warrants consideration in maintaining thermal body comfort. The purpose of this research was to determine the clothing preferences of elderly consumers indoors during cold weather. Four hundred and fifty questionnaires were administered at three locations. Results from the study revealed that comfort was the most significant factor in selecting warm clothing. Although the respondents had implemented the effective use of clothing to achieve thermal comfort, the use of supplemental heat, and control of thermostat setting for heat was more prevalent. Suggestions and recommendations are made for practitioners who would address the issues of clothing for thermal comfort and energy conservation.

Occupant movement and the thermal modelling of buildings

Conventional computer models of the thermal transfer processes and energy consumption of buildings treat occupants as little more than fixed metabolic heat generators impassively experiencing the prevailing indoor environment. However, occupants do move around inside spaces and may experience several thermal environments within the same space. The computer model FENESTRA has been developed to include mobile occupants: their thermal comfort and the consequences for energy consumption. The model predicts that a mobile occupant can experience improved thermal comfort compared to an occupant fixed at the centre of the same space. Implications for both the size of cooling plant and thermostat settings for cooling are discussed. Finally, FENESTRA modelling provides testable hypotheses regarding occupant movement within spaces. If such tests were to be performed they could be used to validate and improve the FENESTRA model itself.

Predicting air conditioner load curves from energy audit data: a comparison of predicted and actual air conditioning data from the Athens load control experiment

An approach for estimating air conditioning load curves based on household duty cycles is presented. The duty cycles are calculated from heat transfer rates using household audit data, thermostat settings and outdoor temperatures. The fit between the load curves estimated from the duty cycle model and load curves calculated from measured data for households where customers set and forget their air conditioner is presented. The air conditioner and heat pump data were gathered during the load control experiments conducted in the summer of 1987 on the Athens Utilities Board distribution system in Athens, Tennessee. Data collected on days when there was no control were used to evaluate the concept of the duty cycle coefficient which was then used to calculate the duty cycle of heat pumps and air conditioners. The theoretical calculations based on the model are compared to actual measured data and are found to be in close agreement. >

Hypothermia and energy conservation: a tradeoff for elderly persons?

For many elderly people, residential energy conservation options are often limited to little or no cost measures such as reducing their winter nighttime thermostat setting. As a result, conflicts can arise between the need to preserve health and the necessity to conserve energy. Under these circumstances, accidental hypothermia is an important and growing concern. This study examines the association between concern for health and the adoption by elderly persons of a lowered winter nighttime thermostat setting. Evidence from two surveys of elderly respondents who maintain separate owner-occupied residences shows that health and thermal comfort concerns are the major reasons for nonadoption of this energy conservation measure. Methods are presented for increasing energy conservation while maintaining a healthful home environment.

Energy conservation: changes in heating practices by Alabama residents

Over one‐half of all the energy consumed within the home is used for heating. Any effective campaign to conserve energy must convince consumers of the necessity of changing patterns of behaviour related to heating and improving the energy efficiency of their homes. A telephone survey using a random sample of 445 Alabama households was conducted to determine changes made by consumers in heating practices since the 1973 oil embargo. Descriptive statistics, chi‐square, and t‐tests were used to analyse the data. It was found that the most common change in heating practices made by Alabama residents was to reduce thermostat settings. Other changes included the use of supplementary heat or improvements in building shell efficiency. Supplementary heat was used more frequently by higher income households, by Caucasians, and by households containing young family members. The improvement of building shell efficiency was found to be associated with higher income and Caucasian households.